Tridentine Masses are certainly legitimate and a lot higher in terms of cultural form than Novus Ordo. No Catholic disagrees with the validity of the Tridentine Mass or the Tridentine sacramental rites.
Is the Novus Ordo Mass a legitimate Mass? If your answer is no, stop the schismatic troublemaking and advertising and mind your own business.
As you say. There are numberless abuses within the Church, but to some extent that will always be true. In fact, in some periods things have been worse. For the believing Catholic, no amount of abuses can be a reason for leaving the true Church and going into schism.
In the early disputes between Erasmus and Martin Luther, Luther was often closer to the truth than Erasmus, who among other things lied to the Pope about his age in order to get himself dispensed from his monastic vows.
Nevertheless, Erasmus chose to stay within the Church while Luther chose to leave it. Luther's decision had serious consequences, down to the present day, whereas few people now care what Erasmus's theological opinions may have been. Heresy is bad but schism is worse, because heresy is more easily correctible.