Right. So. Let's assume they didn't make much money by selling the game. Your amazing business solution would be to what, make even less money by undercutting their MTX revenue as well? Then again, I'm not an expert in that, so if you say cheaper skins would bring in more revenue, fair enough. I'll have to take your word on it.
However, you do also realize though that the Santa skin doesn't necessarily cost $20, right? If you'd buy, for example, the $19.99 Atom package of 2000 Atoms, you'd get 400 extra. You get 5000 for $40. However, the point is, you can have 2000 Atoms in game right now, without buying a single Atom more. You want the Santa suit for $10? No problem, buy the $9.99 package for 1000+100 (1100) Atoms, and spend those 900 Atoms you've collected. There you go, a $10 skin.
Now, if it was even cheaper than that, let's say 1000 Atoms... Well, people already have that. So, nobody would buy more Atoms with cash, when they could just buy it with the in-game earned ones. Not much revenue for Bethesda there.
So, bad revenue from sales, bad revenue from MTX sales, and would people still expect them to keep developing? Oh well, of course not, because these are probably the same people who haven't played the game and are frothing at the mouth yelling for the game to die. For what reason, I have no idea, since it's not going to help them one way or the other whether the game exists or not. Unless there's some completely twisted logic there, thinking that if Fallout 76 fails, Bethesda and Zenimax are just going to go to Obsidian and hand over the Fallout IP as a Christmas gift. Hahaha!