I wish they would do something to fix this. I get that we probably can't stop the "here's a level 2 bidoof now gimme Rayquaza" requests, but something to stop the "I want a level 1-10 Xerneas. I don't care that this is uncontainable legitimately, I will put this on the GTS because I can." would be nice. Some kind of filter that measures legendary levels and prevents asking for something completely uncontainable is basically what I want. Also, when people put in the message "6IV for 6IV" or "shiny4shiny" there is no way to enforce that. It's basically the honor system, and Pokemon + honor system doesn't work well (just look at the barrage of freshly caught Bunnelbys in Wonder Trade).
All they'd have to do is include a summary page where you can check out the nature and ability of the Pokemon. A way to verify IVs (like through the in-game 6 status symbols showing up black by default when a particular stat is maxed @ 31) would be nifty as well.
This would be amazing. Summary pages need to be on the GTS, always have been, that's common sense. But the idea of markings being handled by the game instead of player discretion is a fantastic idea.