No copy-paste is a non-starter for me as well, and probably the largest single reason why I still am on i3-gaps. I still like wallpaper mostly because it's nice to add some light transparency to console windows. I3-gaps, for me, was initially because I had a very, very old computer only. This thing had been retired by a corporation three years prior; ancient i3 CPU. With i3-gaps, it ran nice and snappy; on Windows 10, it largely choked. I've appreciated it ever since.

One of the biggest draws is keyboard-friendliness: you don't have to use a mouse to navigate, ever. Nice for those of us who already prefer programs like vim that allow keyboard usage, and can increase productivity. It's also good for multi-window setups (having more than one open), though some people who use tons of windows use bspwm (represents windows with a binary tree).

Vanilla i3 is also keyboard / low resource friendly; for these things i3-gaps is no different than vanilla i3. Having a wallpaper or transparent terminals never did anything for me but maybe become distracting.