As far as I'm aware Rockstar would like the game to stay as authentic as possible which sadly rules out Steampunk giant spiders and Back to the Future train. I like that aspiration though. However I do think the game needs an awful lot more activites (Both PvE and PvP). There's going to be loads of professions and things to do that they could add. The same with cosmetics. I just don't think they make enough money from the online to make it very worthwhile though.
At the very least I'd reduce the cost of fast travel significantly and place down more vendors. Every settlement of a certain size (Especially the towns) should have a the full compliment. Sometimes you have to trek for miles just to find a butcher.
Level 65 to be able to buy a fast travel point for you camp is pretty bad too. I'd negate the level requirement for that and let people buy it with gold early.
I see the game as more a "Wild west life sim" than a gta chaos engine.