I tend to disagree. Why would this acquisition by Microsoft be bad?
Are they actually a monopoly? If yes, what exactly do they have a monopoly on? Video games? PC Games? I would argue neither of them.
They are not the only provider of video games. Far from it. There is soooo much competition in the video game market.

What they should really tackle in my opinion are all the exclusivity agreements. Cause those really hurt consumers.
Want to watch the premier league? Better buy a Sky subscription for 30€/month. Oh, you are not happy with what you get? Well, don't watch the Premier League then. Go watch the Bundesliga, or the Austrian Bundesliga. Hmm what? Oh yes, they are also only on Sky, so if you want to watch Football at all, buy Sky or go to the high seas.
THAT is much worse than Microsoft just being a giant.

You could also tackle the exclusive licenses in video games. FIFA selling their licenses (nearly) exclusively to EA is a very big reason why EA FIFA got as big as it got.

TLDR: I don't mind monopolies as long as they don't abuse their market position.