I know render distance is working as intended, and that there is a hardware limitation to contend with, but I'm skeptical about using such a low value for the limit on Realms worlds. (This goes especially for Bedrock, since it's better optimized and has simulation distance on a separate slider.) Even just 16 chunks would a nice improvement!*
Either way, if hardware limitations are the only problem, I for one would certainly consider paying a premium on my Realms subscription (within reason of course), if it meant I could have access to more game options such as render distance. Maybe there could be an additional subscription option for this? The render distance might be a deal-breaking issue for many players, so I think something like this would be Good For Realms! It would at least be worth polling the community to see if others feel the same way.