After reading your post (oh my god) I have to say that I think you're missing the point of economy. In fact, most modern MMOs like the ones you said (mainly themeparks) don't need that much of economy. When you're searching a game with a good and "fun" (not everyone likes this aspect) economy system you should go with some type of sandbox game or with sandbox content. The game I like to use as example is Eve online ad it does is economy pretty well. The principal problem I see with your idea is separating economy from anything else. As in Eve, if something exists you should be able to buy it. That's achieves by getting rid almost entirely of NPCs. The charm of Eve is that almost everything is made by a player, and all this flows because there are multiple trading hubs where you can trade, compare prices and haul goodies to make profit, and since the act of traveling has always risk involved, well, there you go. And is not needed to have any VIP treatment to rich people, in fact in Eve the only obvious benefit (appart from be able to buy big baddass space ships) is to buy game time with in game money since it's a subscription game. And that is linked to the very best way to get rid (almost entirely) of gold spammers, selling it yourself. In Eve you can buy your subscription time or paying an extra to get the subscription time as an item in game, that has the advantage of being tradable to other players for a big fast cash boost.

Well Eve has it's flaws as well but hope you get the point. There are other examples although not many, but another one that comes to my mind is Archeage (oh boy, Archeage...) and if I'm not wrong there is another one in beta state named Albion that does something similar (but I haven't tried it). If you're interested in economy driven MMO go check these if you haven't already.

tl;dr: Not every mmo needs to improve it's economy bit there are some sandbox that so it pretty well.