An example:
I thought a subscription payment model was a good idea, having been a long term fan of warcraft.
I changed my mind recently, having tried "Guildwars 2". There seems to be a HUGE amount of commonalities with this title, but for a LOT of reasons, it's not a game I would pay monthly for. Lack of roles made for boring repetative gameplay. Lack of LFG functionality made one of the most appealing aspects of the game inaccessible or awkward. Lack of roles also lessened the feel of teamworking and adding value. It felt like half the glue that holds parties and guilds together just wasn't there. All in all a very disappointing title, which is based on monthly subscription would be unlikely to last out.
I can only hope for a better implementation with ESO. That said, going by the predecessor, Skyrim, the flexibility and design allowed someone to specialise in being tanky, healing or dpsing in many ways. The devs and designers ultimately have a very tough challenge ahead, and one which seemingly small decisions can make or break the future of the title.
Will be interesting to see the outcome.