Why? Management changes, engineers change, everything changes. Saying "No" just because it's Microsoft is incredibly short-sighted.

And even if it were so: the product as it is today was mostly developed while it wasn't even under Microsoft.

No, it isn't short-sighted. On the contrary it is a matter of letting Microsoft earn their trust again at a reasonable pace after almost two decades of systematic abuse. The Halloween documents where published 1998 and it is only the last year or so since they've begun dipping their toes in open source waters. They've thoroughly earned their shame.

Besides, even if everyone at Microsoft has changed attitude that's no excuse. Microsoft has had five years since the acquisition of Skype in 2011. Isn't it, by now, time to stop blaming their predecessors and own up to the current state of affairs?

It's not only that the attitudes have changed. What percentage of the people working there in 1998 are still working there?