The reason why those trades are there is cloning. They're all exploiting the cloning glitch and putting up ridiculous requests so they don't actually got through (You'd be amazed how fast proper trades go through actually).
Honestly, even if people find a cloning exploit again, removing the request to seek a Pokémon you haven't seen will make the GTS a bit better, as depositing Pokemon and requesting them does work much better.
But I thought the cloning glitch was gone since Platinum? Surely all those people aren't stupid enough to keep trying?
the problem is that if anybody thinks like that and put an early route pokemon then wonder trade will really be useless.. people need to have a leap of faith and actually offer something at least decently rare in order for this option to be any more then a glorified oalternative for a normal trade that nobody would use..
There will still be a GTS function, which hopefully will put up restrictions on what you can request and for how long you can keep trades active to keep people like that out. As for Wonder Trade, I don't know about other people but I'll be putting up extra Pokemon I catch and breed of quality that I don't need. Hopefully that will become something of a common courtesy.