But really the ideal job is the one that's so much fun you don't even care about where the job ends and the personal life starts. And the other way around as well. Unfortunately there aren't enough jobs like that, leaving many people stuck on the 'the ideal job is the one I can forget about when I get home'-situation. But that's just because you haven't found the right job yet. Or because you've simply given up.
Or because you have a child or a spouse, and you damn well do care that you spend some time interacting with them regardless of how much fun you might have doing other things. "Work/life balance" isn't about "work/fun balance", it's about having responsibilities to other people than just yourself and your boss.