It depends on what you mean by "thinking mind".

The most common definition of a thinking mind in the context of meditation traditions refers to the "stream of chatter", a stream of rigid verbalization and grouping of experience that runs on autopilot. If this is your definition, which is also referred to as "ego" or "negative ego" by some traditional meditation schools, then, yes it is a hindrance and should be diminished.

There are two words here: Rigid and verbalization. If your interpretation of reality, which is synonymous with the experience you use to define your words and other symbols, is rigid, that means it cannot change, and because the world is constantly changing, it means your interpretation of reality will become ineffective. In other words, the main problem with verbalization is its rigidness. That is the approach that the various chanting schools of meditation take- and I count Western style affirmations and hypnosis among them- "There is nothing wrong with verbalization, let us change the verbalizing to a more effective version of itself, and all will be fine." There is much good there.

Other schools take the approach a step further and attempt to cease verbalization itself- Zen Buddhism, some types of Hawaiian "Nalu" and some of the more mystical elements of the Abrahamic religions do this. The stopping of verbalization leads to unfiltered experience, uninterpreted by symbols. This leads to experiencing the more refined aspects of reality, all the way to sensations of unity with God, which is commonly referred to as enlightenment. Common side effects are a desire to help other beings, and a lot of loving spontaneous things happening unplanned. The downside is that in the beginning stages, because there is no instruction on how to verbalize properly, any existing habitual negative verbalization and the associated low vibrations will come right back so there is a need to meditate for extended periods of time.

This gives ride to an alternate definition of thinking, the one that yours truly prefers. When you meditate for extended periods of time, obviously you do not stop existing- your rigid, automatic verbalized thinking does. But if thoughts are things, and you are made of thoughts first and foremost, and if the world is made of thoughts first and foremost, and you can manifest reality by thinking, then certainly there must be more to the idea of thinking than verbalization, or experienced mindlessness-meditators would simply disappear.

I'm not saying that never happens, but more commonly their negative beliefs disappear, and they are still there, happily vibrating, and hence thinking away.

In other words, stopping your thinking is done to get inspiration, which leads to quite simply thinking better, more appropriate thoughts.

This definition of thinking is more neutral. You have experience, which is your thinking. You can use your power of thought to create thoughtforms, and if you have a lot of those, you can simplify your thinking by treating them like little connected dots, and to an extent, that will work- it's a process commonly called "modelling".

So here is my recommendation based on these ideas.

There is nothing wrong with your thinking mind- Buddhists think. Someone has to decide to build the monastary, and someone has to decide who gets to be abbot, and someone has to make up the rules on how to dine. That someone has already done that, in the more traditional schools of meditation, makes no difference- you still need to think to execute the daily routine. So thinking obviously does not stop in the most enlightened people on earth.

Verbalization may stop for extended periods of time, giving rise to more inspired thinking by those practicing it's stoppage- but verbalization can also be recreated in a more inspired form through a process of trial and error, which also leads to more inspired thinking.

So the two takeaways are:

(1) Be aware your thoughts and how you feel about them

(2) Be aware that no matter how sensible and well aligned your thoughts seem, they are completely arbitrary and it is your job to change them in some way until you feel good about them

This leads me to a less common definition of what you referred to with the thinking mind- the Huna one, my favorite.

It is common to distinguish between two kinds of mind, because it is such a universal experience, but there is a lot of disagreement to what the criteria are to make the distinction. You can distinguish by logic or feeling, you can distinguish by how aware you are of the processes, you can distinguish by various things that you value, and you can randomly assign various characteristics.

By far the most useful definition, in my opinion, is to distinguish by whether or not you can control it. This leaves the definition of the mind-in-charge with only one function: To direct attention.

Go through your life- your attention is the one thing that always, always, always, you have absolute and immediate and total control over. Your attention may drift, but that's because you're letting it- once you notice, you can just tell it what to do and it will do it. Always.

Everything else can be done consciously or unconsciously- you can breathe, but you also just breathe, for example- same with daydreams and even logic. You can habitually reason and verbalize- that's where the "chatter stream" comes from in the first place. In this view, the chatter stream is not the ego at all, it's just habitual thinking based on negative beliefs. A much more useful metaphor, in my view. You can do have all kind of verbalization and reasoning going on without being really all that involved- that's where the rigid worldview comes from in the first place. And you can't control any of it- that's why you need to meditate at all. If you could control your thought processes, why use a technique? Just be enlightened and that's that. But you can't- but you can use your consciously directed attention to influence your automatic processes to sit on a cushion and focus on your breathing. That you can do. But as you are expanding your awareness this way, you are not diminishing your ego or diminshing yourself- although you are changing your negative beliefs into positive ones- you are simply using your natural function of directing awareness to become more aware of your automatic processes in order to influence them for the better.

In Huna, where these teachings come from, the director of attention is called the "Lono", and all the automatic processes (which do also contain your body, your feelings, your memory, and your connection to the universe, along with your habitual thoughts or beliefs) is called the Ku. In Huna, you are taught to treat it like a friendly barn animal- gentle, loving and firm, like guiding a donkey to the market with lots of green grass everywhere. I love this metaphor- it's so practical and familiar from my experience, and encompasses all traditional teachings I know of.

To take this long story to an end- when the metaphor is confusing to you, change the metaphor. Once you have your clarity, you can always explain the other metaphors within terms that work for you, to regain your understanding- like I did with my understanding of Zen and affirmations, which I knew about before Huna. As a general framework of understanding, in my opinion Huna is the very best there is- and they do say that it is the remnants of the knowledge of the star seed who landed on the lost continent of Mu, the highest peaks are which are today known as the Polynesian Islands.