I own ESO and for an ES MMO it's not bad, but there are somethings about it that don't translate well from single player to MMO. A card game based on ES seems rather pointless to me. But believe me what I said isn't as harsh as it could have been. Right now Konami has that harshness trophy in platinum. I just feel that ES should remain as it is when we were first introduced to it. It's popular so why mess with a good thing and risk diluting it?
It's for branching it out as a franchise. Neither of these are main titles thus they're nothing to be worrying about. It's different in the sense of like, say, Castlevania, where after Order of Ecclesia came misstep after misstep (Judgment, Harmony of Despair, Lords of Shadow, Mirror of Fate, Lords of Shadow 2). While two of those were spinoffs (that did horribly, mind you), the next three were main titles (the first of which did well, but the next two did badly).
While a card game may seem pointless to you, there are people who play card games a lot and it may be of interest to them. Hell, it might even be a fun card game. But I don't necessarily think the card game is anything to be worried about.
Elder Scrolls has always been a good thing, yeah. But Bethesda is a business, and if they find a little side-project that they can make money off of, generally they'll go for it. Besides, I have no doubt in my mind that they have a completely separate side group handling the card game. The whole thing, in all, is just building on a brand name. It's definitely something that calls for confusion, since no one saw it coming. But say Bethesda is "losing their grasp" on what Elder Scrolls is is a bit too harsh a statement for this.