For shorter texts/smaller photos, and for wider windows, I think it can end up looking worse than what we currently have.
I don’t have data on how many Anki users create longer cards vs shorter ones. If it were heavily skewed in one direction, that might be an argument for the change. I suspect it’s a bit more balanced than that, but I’m not sure.
One other thing I should note is that we encourage users to stick to the minimum information principle, and such minimal cards tend to look better when centered.
This would leave users who want large images to either use a shared deck, or to figure out the margin/padding settings, which is not ideal.
While not something I feel particularly strongly about, I should note that I originally picked Arial because it or its fallback looked fairly similar across the various platforms.
Spitballing: maybe platform selectors could be used to make it clearer why multiple fonts are listed? e.g.