>>715825000She's underrated because she effectively did not exist for many years. At best she was used as an alternate universe series of games where Mario is fighting DK and those games were all handheld tier. Even within those games she was not allowed to do much. Hell even in Bananza it's young Pauline who accompanies DK not the regular version.
Unless Nintendo steps up in her usage she will eventually continue to be obscure like Rosalina.