Arkane were good devs from the get go - Arx Fatalis is quite loved in CRPG community and Dark Messiah of Might and Magic was really fun game. I don't think that Bethesda put many creative constrains when they acquired them, though I personally don't find any of titles under Bethesda to be as good as when they were independent.
I looked up their body of work and it's smaller than I expected, which explains why I'm not familiar with them beyond Dishonored. They contributed to Call Of Duty: World At War ( my fav COD game ) and Bioshock 2, which I also enjoyed, but they've only made 5 full sized games, plus the dlc's for Dishonored 1 and 2. Dishonored came out in 2012 on last gen platforms, but it was probably my personal 2017 GOTY.
Chinese food for breakfast