It's a generally accepted adage that ideas are cheap. Bungie generally does their own thing, responding only to edicts from above or to overwhelming community pressure. Your best shots at getting your suggestions taken seriously are to want the same thing as millions of other people, implement your ideas as a mod or as your own original game, and/or get yourself hired. (Yes, but good luck)
Voidevil: So there's no way of making a suggestion then? But I don't know how to program games just yet:'( I want to but I can't :'(
You may always make suggestions by merely making them on Bungie.net.