Most people have a custom color set on their Xbox (or Xbox account) that they find more appealing to them. What would be even cooler, is if this choice carried over into Minecraft itself. Instead of always having the green, you'd see whatever color you have selected yourself. For example, I would see orange since that's what I chose.
This feature may reduce the high visibility aspect of selecting buttons if a poor color is chosen, but most of the available colors (and there are not too many at the moment) would work just fine.
This suggestion applies to Minecraft: Bedrock Edition only.
IDK if that's as easy as it sounds, maybe i'm wrong, that would just be more information retrieved from your Microsoft Account and a longer sign-in process