It's much easier to perform an exercise with crappy form than it is to work hard and maintain perfect form at the same time. (justinkavanaghfitness.com)
But, it should not happen at the expense of crappy form. (acaloriecounter.com)
(If you really can't squat any deeper without using crappy form, then start stretching your quads and hip flexors to improve your flexibility.) (kingofthegym.com)