Vista tried a lot of new stuff, most of it was meh, then 7 came along and reined it in a lot, then we got 8/8.1, again, changing a ton of stuff unnecessarily in the name of updates, then 10 tried to strike a middle ground. Now we have 11, with its exceedingly aggressive hardware requirements and forced changes. With 12 we'll probably be back to MS trying to compromise so people move on from 10.
I think MS's issue with OS planning is that they really don't understand "don't fix it if it isn't broken", after every successful Windows version they get overly ambitious, change too much and push users away. Then for the following release they have to consider the fact that a large portion of their userbase hasn't upgraded, so they actually pay attention to feedback and try to compromise between what people want and what MS wants.