I tried the no-lid game for a bit. It wasn't a whole lot of effort to maintain the water level since I was doing 50% water changes daily, and the tank only lost about 2g/day due to evaporation (so maybe my total volume changed was 48% daily). The only time it became an issue is if I had to let it go for a few days at a time. My water is pretty stable out of the tap, so I could just top up from the tap (prime added, of course) when needed.
There were two reasons I ended up getting/making a lid. 1) I had the dreaded jumper and 2) I wanted to add some pothos and such on top to grow out, soak up some nitrates, and add some intrigue to the aquarium.