No, it's not really Google's ultimate responsibility, it's the user's - the same way that it's not a car manufacturer's responsibility for your gas mileage if you do mostly city as opposed to highway driving, decide to keep under-inflated tires on your car, leave it idling for hours, drive over and above the speed limits, etc.
If it's something with the underlying OS, yes, that's Google's ultimate responsibility. However, if it's an app causing the problem, that's not their responsibility. They can't go through every app in the store and try it on every device in every combination. Completely unreasonable. Even Apple, which has a much tighter lock on their app store, still has apps that come through that drain their devices batteries inordinately, apps that have bugs, etc.
As for apps? That's the user's responsibility. For instance, it's well known that some apps, such as Facebook, are known to wakelock, drain the battery, etc. If a user still sticks Facebook on their device, they can't then complain about battery drain to anybody but Facebook, as the response from everyone else is just going to be along the lines of "well, we said the Facebook app was crap and drained the battery and told you not to install it. Tell Facebook to fix their junk apps and uninstall it from your phone or deal with the drain."
Ultimately, the only way it would be 'Google's responsibility' is if Google didn't let you install any apps, or only let you install apps they themselves created. That kind of thing wouldn't go over well at all.