Well, as someone who gets 150+ emails per day let me say to everyone who cares about this: switch to K-9 mail tool!
Not only does it have a "mark all as read" menu option (3 clicks to approve, but better than nothing), but it also works better than the default tool and integrates with docs to go. The only feature it doesn't have is a merged multi-mailbox view, which I do kind of miss.