It's not just you. Two climbing systems really opens the door for not only higher safety, but more positioning options. Also, the older you get the more aware you become to just how busted up you could get from even a short fall, and just how much longer it will take you to heal up if you get hurt. It slows you down, but that's something else most people stop caring about as they age. In the grand scheme of things, just getting it done is probably a bit more important than trying to get it done faster.
I'm sure production climbers have a different view on that, though. My wife used to help me on jobs, sometimes, and she couldn't stand watching me climb on one line. When I started using two, she got over that when she realized that even if something went bad with one, I wouldn't actually fall out of the tree. Might smack a stem from a big swing, but it would take a lot of bad things happening for you to actually fall.