I felt the need to know, particularly if I'm adding more smart copies, often for extra keys but who knows what other reasons (extra verses, different arrangements).
Add a Song - on the fly shows Only the Title but does (I now spotted) add copies in a "#" section for each letter, but without any key information - tricky.
In the regular Set List, it may just be a confidence thing. I can see the key but with a large repertoire, I feel the need to know whether it's my original or a later modification. Probably just me then - but I find that the fewer things I have to think about, live or even last-minute updates in the dressing room, the easier everything becomes. I like stuff to be obvious and not require more thought than necessary because I sing, play, run the mixer and either solely or partly, BH too.
I have added tags for now. There - I admitted it.