What I'm highlighting here is that I have noticed a tendency for Pixel art games made with Construct on Poki to load slower for players, to the point of significantly affecting the player bounce rates
Do you have measurements you can share that prove this? I find this surprising - pixel art games should not have heavy art assets by any stretch, and a good CDN should not have a problem with something like 100 small files - with modern HTTP 2+ those all just go down the same connection efficiently without having lots of per-request overhead. For example the Construct editor is 1000+ separate requests to load the editor - mostly lots of small files - but it's served cached via CloudFlare CDN over HTTP/3. A cold load takes <1 second on my system (with a good connection, but still). So I have to ask, what measurements have to made and what has led to identifying spritesheeting specifically as the cause of it?
Again, in the use case I am defending, memory usage is NOT the bottleneck.
I know, but we have to make something that works for all sorts of kinds of projects, not just specific ones. If we add a setting, sometimes people change the setting, forget about it, find their project starts crashing, and then leave us poor reviews or end up contacting customer support. So we also try to avoid features that make it easy to shoot yourself in the foot like that.