Well they don't if they are not pleasing the fans. It less about making the perfect exibit of a game and more about making something that is playable to fans of TES. I don't care if this game sells 20million copys, if it doesn't appeal to me then I won't buy it. It would be a shame to see people who wanted a different direction left in the dark for the reasons of profit.
Profit is the real reason game developers develop games. I wish people would realize that. They don't do it out of the goodness of their heart. If a massive number of people like the product, then great.
Bethesda Game Studios, with the Elder Scrolls core series, has give gamers who want an awesome single player experience exactly that, earning many repeat customers with each new installment in the series
Zenimax Online Studios, with The Elder Scrolls Online, will be giving gamers who want an awesome massively multiplauer experience exactly that, and will earn many repeat subscribers.
Now if there is an overlap of players from both genres of Elder Scrolls gaming, so much the better for both studios.
I should point out that not everyone who played the Warcraft series has played World of Warcraft. Not everyone who has played World of Warcraft has played the Warcraft series, either. There is an overlap in terms of those who have played both, and it's a good thing for Blizzard
And again, not everyone who has played Star Wars: Knights of the Old Republic are playing Star Wars: The Old Republic. Not everyone is playing Star Wars: The Old Republic has played Star Wars: Knights of the Old Republic.
My point is, that Zenimax is not necessarily targeting players of The Elder Scrolls. They are targeting MMIO players and players of The Elder Scrolls series who also would be interested in playing an MMO that is based upon the IP. And MMO is going to be designed with and based upon mechanics that are best suited to that type of game. But I will say this much. Commercial viability of TESO after its 30-day trial is up will be based upon what it doesn't have in common with other MMOs, rather than what it does have in common with them. Those who would take a break from a game like WoW to check out another MMO are looking for a different experience. If they do not find that, there is nothing to really incentivize switching games. That is something the post-WoW MMO industry needs to learn and should have learned by now.
I will give TESO a try. But I will not continue to play it if it offers nothing any more or any different than what I can find in WoW, LotRO or any other MMO out there. It won't matter to me how closely TESO follows the TES lore. If it looks like every other MMO and plays like every other MMO, then it will garner my lack of interest like every other MMO.