For some, the search is also part of the fun. I enjoy trying new things. I do photography because I enjoy it. Why would I stop doing something that's one of the things I like about photography?
Might make better images - but I honestly kind of doubt it, unless ALL one does is shoot a bunch of films and try a bunch of developers. It's certainly possible to get to the point you're using nothing but stuff you really don't know what to expect from in even general terms, but that's an extreme that most of us don't engage in or advocate.
I think this was much more important in the days of mostly graded papers when VC papers sucked. It was more important to choose a paper/developer combination, then choose a film/developer combination and work out your development times to match the negatives to the paper. That will still produce quicker, easier prints, at least starting straight prints, but the printing has much more leeway now.