In the past 18 months I can't recall seeing any new avatars. Not that it's WGT's primary concern or focus but not ones to shy away from making $$$ I'm surprised they haven't capitalized on expanding upon the current choices.
It's not rocket science - changing shirts, skirts and trousers, shoes with an alternative colour or adding a hat or some other accessory isn't exactly a developers nightmare for the mildly competent.
Just one idea I thought would be nice (though it would be a WGT freebie), would be to have an avatar added to the existing collection upon moving up to a new tier. For example:
Amateur:
Pro:
Tour Pro:
Master:
Tour Master:
Legend:
Tour Legend: