Investors should scream at stuff like this. How many things could millions of extra dollars buy? For one thing, maybe they could have acquired 4 or 5 additional companies, patents or other IP. If there was any chance that they could have done this for $500 million or $400 million or $50 million, that matters and should have been investigated thoroughly. Those saved millions of dollars can also be used to employ a bunch of people on projects for years (heck, sometimes entire applications are written by one or two people inside a company, and they might build something really cool that can be sold).
Microsoft has lots of money, sure. But this kind of spending isn't thinking long-term. Are they guaranteed to have this kind of money in a few years, even? There may be a time when they're completely incapable of making a key future acquisition because they overspent on crap like this.