You're certainly right about the fact that my difficulty to find something wrong with this feature speaks for itself. And I actually realized that were there other cases where using parenthesis might be significant (like in a token when you don't know what's in the upper level rules), named captures would make an easy way out.
So from my humble point of view, it is a non-issue. The over-riding principle should be that change involves costs and should be avoided unless the benefits significantly outweight these costs.
I'm not going to argue with that, the answers I received helped me see some of the aspects of the matter I might not have grasped on my own, and I do see now that this is indeed little trouble. I can go back to my regexes and be content to not only know how they work, but why it's OK that they work like that :)