I think the system that allows multiple RTPs was a very good idea, it just never got much use. In fact, most of us make our games not need ANY RTP when we distribute them. Having someone download the RTP in order to play your game (if they don't have RMXP) takes more time from them that they could spend playing your game. But having EVERYONE download some random RTP you made (even those who own RMXP) to play your game will make very few people play it. Who wants another RTP on their machine just so they can play your game?
But if you make countless resources, some in each category, then making an RTP to distribute (and an installer for it), would be a great use for the system. The problem is no one has taken advantage of the RTP system (to the extent of my knowledge), but it would be great to see some RTPs created. (I'm surprised there aren't Zelda RTPs yet, since I've seen so many graphic rips)