Given the lack of real difference between the Gold and Silver, hard to tell that they really DO love the subs. I agree that they SHOULD, for all the reasons you mention, there's just no incentive to DO it given the lack of bonuses, perks, access, or limitations. Silver can get you almost the exact same stuff, for free. Gold still has to pay for most of the stuff (everything's Zen store, really), so why not save the sub money and buy it directly?
If i took all my sub money, plus what I'd bought separately, I'd be way up if I hadn't subbed, and I'd have all the same stuff, access, etc.
Should be more stuff for the Gold/LTS members, to encourage them to hand over large chunks of money (which pays for further development). Things like free sets of keys to the constant lockbox nonsense would be no-brainers. Discounts on the Zen store over Silver members, etc. Pick you own ideas, but there's no real perk to paying upfront anymore.