It's two vastly different things and I think people have vastly different expectations. Mojang are Minecraft, whereas Rare were arguably the greatest non-first party studio of all time. Lots of people failed to realise that the Goldeneye/PD teams had left Rare prior to the sale or were confident that it was the Stamper brothers who made the magic happen.
This seems (at least to me) to mainly be an IP acquisition, Notch is leaving (but had checked out of Minecraft long ago anyway), I'm sure I read that the other two were also leaving.
So I can't really see how the comparison was warranted? Notch has said he doesn't ever want another massive success so Mojang were never going to turn into the modern Rare.
Oh I know that. What I was saying was this apparent outcry of 'Microsoft will kill Mojang' was because of the Rare thing.