An acquisition is often played up in the press as a "touchdown" for the company doing the buying. The narrative of Smith Widget "gobbling up" Jones Wadget after years of competing is too easy to avoid. And of course that's the story Smith Widget wants to convey: strength, preeminence, market domination.
But it's really a confession. When Oracle bought PeopleSoft and then Siebel it was a confession that they couldn't develop applications on their own. When HP acquired Compaq it was a confession that the PC market was headed downhill. When you can't build products or acquire customers yourself, you buy them. Either way, an acquisition is all too often an admission that you have more money than ideas.
If Google bought Monster, it would certainly cause some to seriously re-think the "Google world domination" meme that currently underpins their public identity. Their strategy as best as anyone can tell is to penetrate markets from the bottom up via search. This is promising but remains largely unproven. Buying Monster would for many be a very public admission that it won't work where there's a pre-existing market.
It will happen eventually, and the world is moving faster. The Dutch East India Company lasted two centuries. Ma Bell made it a little over a century. Microsoft wasn't 25 when Netscape had the Street talking about the end of Bill's Billions. Google turns 8 this year.