Yes dhikr in it of itself is suitable for everyone, in fact we have all been commanded to do dhikr and to remember Allah. I'm not saying to not do dhikr at all. I'm saying that certain forms of dhikr have been prescribed by mashaaikh in order for people with certain temperaments and at certain levels to progress. A shaykh looks at the whole picture and then prescribes dhikr for the betterment of one who is asking. It's sort of like a doctor prescribing medicine for you, he will look at the whole picture and then tell you what to do. These days the majority of us have weak hearts and can't handle some of the methods of zikr written in books of tasawwuf, sometimes too much dhikr could result in dryness of temperament and then turn a person away from Allah. Like you said, the purpose for dhikr is to please Allah, obviously, what i'm saying is dhikr is the sword, you need an expert who knows how to handle it in order to make the proper cut, that is if we want to know how to become closer to Allah we find someone who is already close to Allah and knows how to get there, and commit ourselves to his instructions. If we were sick we wouldn't down a bunch of bottles of random medicines because of course, medicine is for everyone to become healthier, we would ask a doctor which medicine is suitable for us and for our particular disease