Although I don’t have anything against the idea of this proposal, I am against this proposal because adding a “simple button” is a complex implementation from a dev standpoint. And right now, our most scarce resource is developers.
And I think that most people that are willing to give up their staking rewards are already doing that (through a normal transaction to the burn address). Sure, a streamlined process will probably increase voluntary burning, but I don’t think it is worth it (because of the dev-time it will cost).
One simpler option would be putting a banner with the official burn address near the “withdrawal rewards” button: it will only cost to the dev team to tweak the frontend of Terra Station and not a full implementation that requires days (or weeks) and could introduce bugs along the way.