Sure, "I wish to learn about this stuff" or "I think playing with this stuff is fun" are both fair reasons.

But apart from those, I just don't understand how adding the complexity makes my life better. People are saying "VLANS!!!" but why would I want to do that? How does my life improve if I do?

Everyone has already stated what they find VLANs useful for. If you don't think they're useful then I suspect you don't think VMs are useful either.