For one, it's taking a popular IP away from fans who supported it. How can that not be a negative? Second, I don't trust Microsoft whatsoever. Lionhead got axed after being forced to make a GaaS title when they had no experience in that field. Wouldn't surprise me at all to see Obsidian used poorly. Spencer hasn't exactly been setting the world on fire with his first-party decision making.
When a studio that's closely tied to a company gets absorbed, that's fine, but watching multiplatform studios get swallowed up does not sit well with me.
Also, I'm not buying anything from the Microsoft Store. Are all Microsoft games on Steam?
Okay.. you obviously have a thing against MS, that's fine, however I don't understand how its taking a popular IP away from gamers? They are mainly a PC dev who at one stage made KOTOR with the help of MS. Obsidian will still make there games for PC no doubt since MS are a major PC brand.
Lion Head went down hill when Fable 3 arrived, Lion Head just weren't a talented studio anymore. Its not a loss, the IPs still exist and the IPs can still be amazing under another company filled with talent.
Majority of MS games are not on Steam, namely the AA games from Remedy and 3rd party outlets are on Steam with a few exceptions like KI, but there big 1st party games are Win10/Xbox exclusive. Normally the pattern goes like this, if a game doesn't sell or have big sales expectancies on Win10/Xbox they normally get ported to Steam, or games that require a online community. Its MS's strategy in keeping some IPs alive or reviving and keeping alive old communities.
Obsidian are a talented company and some times companies need a good budget to really shine and blow the doors in this industry. MS will surely give them what they need to make a good game. They wont be wasting there investment in a brand for nothing, that's not how they work.