Yeah, but your logic is that somehow if they incorporate big name voice actors into the game they aren't going to be able to do other things, and that's just not true. You think they are seriously so close to wire? Do you think Bethesda is hurting for money? They are simply adding a feature, which im sure they're accountants penciled in in the original budget meeting. Unless you just don't trust Bethesda, I'm not sure why you'd care. Movies could hire no-name actors and save money too, but they don't because they don't have to.
Lets say their voice acting budget is X. With X amount of money they can afford 5 famous actors, and 8 non-famous actors because the famous actors will obviously be paid more. If you take those 5 famous actors out, lets say they cost about four times the amount of a non-famous actor, then you would have 28 non-famous actors all-together, allowing them to have a more varied cast.
Some people would just like a more varied cast (not having all of the Elves sound exactly the same). I mean maybe they're not "hurting" for money, but they're still probably going to try to get by with the lowest amount they can, whilst still trying to have it the quality that they think is adequate. And some people just don't agree that it is adequate. I think this is the case of what happened with Oblivion, but I believe they are changing it with Skyrim (pumping more money in the budget that is, because it just wasn't quality enough).