You seem to have forgotten your image, but I'm pretty sure I know what you're talking about. Short of banning the people who do it (which would be really stupid, this is hardly banworthy) I don't see how else they could address it. As long as there's a text entry field to type whatever you want, this will exist. And removing the textbox would be terrible because it's quite useful for people to specify if they're making a learning party, experienced party, farming group, or whatever.

Honestly I don't even mind it so much, because you can filter the Party Finder to show only the particular duty you're looking for, or you could, y'know, scroll down.