The expectation that something is going to go FTP because most others have done so is based upon the idea that NO MMO can succeed in the market. This is obviously false as WoW is still subscription and still claims around 8 mil subs (7.8 reported by Kotaku in February). What this means is that there is a market, but experience has shown that most MMO subscribers only play one game at a time. In other words, we know that there are at least 7.8 million people currently playing MMOs, and for ESO to be competitive it needs part of that market share.
However this is facially wrong because WoW's sub numbers at one point were around 13 mil, that's 5 million players that have gone missing! These are free agent MMO subscribers floating in the nether, just waiting for a good hook. You ask for a reason why this MMO should succeed? I gave you three yesterday, but I'll give you one major one. It's because these dev's actually care about the game they are creating. I love BioWare, but EA hasn't had the best track record in the last few years. Remember microtransactions in Mass Effect 3, SimCity, BF4? Its because they see themselves as a business first, and an entertainer second, rather than visa versa.
Bethesda/Zenimax has a track record that shows they give a damn about their product, and the changes from beta to release even over the past month shed light on this fact for me. It doesn't have the hype train behind it that SWTOR/Rift/GW2 had, and that's what will make it successful. Instead of people burning out in the first month, this game will give a slow burn to players who are dedicated to the content, and I predict this will drive new people to sub. It took WoW almost 6 months to hit 3 million subs, and at that point the firestorm was underway and they quickly shot up to 7, then 10 million subs. ESO doesn't need these numbers to be successful; an MMO needs roughly 1 million to start exponential growth, but no more than 100k to stay in the black. While it's future is far from certain, this game feels like it has real legs under it.
Now, I do actually believe they will incorporate some sort of storefront within the first year, ala WoW's new store feature, because its a great way to make gobs of cash on the side. Horse armor baby!!! (As an aside, the horse armor marketing guy came to George Mason last month and said it was an hilarious experiment, and that it was the single-most profitable DLC they've ever released!) But seriously, I bet they do not go too far beyond cosmetic items and pets.
I could be horribly wrong. Zenimax could be a bloodsucking vampire just waiting to sell out and make a cash grab. Only time will tell. What matters now is this; ESO is a great game with an epic story, and if you don't play it you are missing out on one of the finest MMO experiences yet created.