Doesn't ZeniMax like some hostility in takeovers they do?
Not via the open market. And not on companies in good shape.
Their targets are studios with decent talent who've been reduced to the edge of bankruptcy by being fucked with left and right by the rest of the industry to the point that being bought by Bethesda is probably one of the better scenarios for them.
Arkane had a string of projects that were cancelled in order to work on another project - Which was then cancelled to work on another project - Which was then cancelled to work on another project - Which was then cancelled to work on another project - and so on, starting with the ill-fated "The Crossing" and going through a billion and one other things with EA, Ubi, and Activision, all of which ended up getting cancelled so they could work on something else. The net result of being bought by Bethesda was that they actually released something instead of deleting the source code for once.
Id software was absolutely FUCKED by Activision and a bad publishing relationship with them. Under Activision:
1. Id Tech went from THE FPS engine to losing literally all of its market share to Unreal and mods of Id Tech (Source, IW Engine) that didn't have to pay royalties back to Id.
2. The value of Doom was tanked by Doom 3 and the Doom Movie
3. Quake was ran into the ground with Quake 4 and Quake Wars.
4. Wolfenstein was turned into a CoD spinoff
5. Id was relegated solely to developing Id Tech instead of games - Which by this point was a bloated mess of technological gimmicks pushed by a past his prime Carmack that didn't age well or weren't good to begin with, all of which made the engine genuinely worse and failed to sell the engine.
6. Activision was going to have DOOM 4 be a CoD clone
To say the least, Id has come a long way since being bought by Bethesda.
Human Head was the exception to my knowledge, and in their case, don't hate the player, hate the game - Because nothing Bethesda tried there was unique.