Theoretically speaking, if a centaur was strong enough to support a human/dwarf/gnome rider wouldn't they just be outright more effective than a normal horse?
>Mount can take care of all the navigation whilst the rider takes care of the fighting and occasional orders.
>If one or the other dies it's probably way easier to get acquainted to a new partner.
>If a taur breaks it's leg it's actually smart enough to rest and let it heal.