Arkane was running into the same problem late Looking Glass was. You're right it can be profitable per dollar but it depends on the sales and the costs of development for what game you're making. If you keep falling below what you need too put the studio in jeopardy.
If Arkane was independent they probably would have closed down back in 2018. So the question is, how much does Microsoft want to spend on Arkane projects that are only managing to fight breaking even?
While I do agree that Redfall was too soon without testing the waters first, it doesn't seem like anyone forced them to do it. Looks like Arkane wanted to go in that direction themselves since they were working on the game before Microsoft acquired the studio and I don't see any evidence Bethesda forced them to make it.