I personally think that what constitutes "good" with regards to how i play is whatever begets good outcomes. when playing a videogame, all thats really at stake is my happiness/enjoyment. measuring how im performing at the tasks the game expects me to complete is only useful insofar as it can improve how i feel. so the "best" way to play is whatever makes me happiest and what makes me happiest is winning, unless its somehow more fun/satisfying to do things in a way where i lose. therefore, an undo button will necessarily make me play "better", because it gives me more options for how to proceed and allows me to freely choose between those options to get the outcome that makes me happiest.
for others, an undo button would make them play "worse", as it would make them have less fun. for that reason i think there should not only be an undo button but also a way to have it enabled and a way to have it disabled. i neither know nor care which of the two should be the default.
as leif said, having a way to have it be verifiably, permanently off for a game would also be a good feature and therefore should be included
thats my two cents