I'd say he's trying not to be remembered as the "Steve Ballmer" of Google. You know - that second-run CEO who drove the company into the ground while keeping the wall street numbers looking good. Cuz that's exactly where he's heading right now.
I think he knows he needs to fundamentally change the culture of the company. He's been making public statements as such. He knows it's a problem that Googlers have been treated as unicorn snowflakes with free massages and all the gourmet food they can complain about, with zero accountability for getting anything done. And despite this obvious rot, most of the world (like everybody here who dreams of a google job) still reveres Google as an idyllic place to work. Which makes it all the harder for the company to admit to itself that anything is wrong.
Cultural change is really hard. And it's not at all clear that he's got what it takes to do it successfully. Googlers are so pampered that any attempt to push them out of their comfort zone is going to get serious pushback. I say this as a former googler. There was a hilarious post on HN not long ago which I can't find where a googler said something to the effect of "no way in hell my manager is gonna make me work."
The entire company is built around solving HARD problems, not USEFUL problems. Obviously they've pulled off a lot of truly amazing things, but that difference is pretty important when your company's entire revenue stream is still coming from key insights made in the late 1990s. To me it's clear they need to change their promotion criteria, which solidifies this and drives so much of people's energy and bad patterns. But the arrogance built into the culture of "solving the world's hardest problems" means that any changes there are likely to insult the fragile egos of all those snowflakes and cause them to go on strike or make the good ones just leave.