Recently TB storage has become easily available and there are several popular decks in Anki that are over 1 GB, so I think general Anki users may not be too concerned about storage.
And there is probably a difference of 10 to 100 times in UV speed between having cache and not having cache, if users are using low spec environments I think communication may be more costly. (e.g., communication costs are high, speed is slow, or unstable and disconnects)
Anki is gradually moving from PyQt to Svelte so it is possible that PyQt will eventually be completely discontinued and replaced by Svelte. (I don’t know when that will happen.)