It never goes higher than 1d10, however.

And it still doesn't with a martial versatile weapon, so what's your point?

Monks unarmed strikes damage die surpasses spears and staves.

That's not how that works. Unarmed strikes NEVER surpass monk weapon damage die. Do you literally not know how monks work. Aside from that, wielding a weapon still ends up being objectively and directly better than unarmed strikes once you account for magic weapons, which should definitely have started appearing by the time marital arts die catches up to your staff.

And again, versatile weapons IN A VACUUM still have no point. They have a point IN THE CONTEXT of the monk, but still none in any other class.