Vaginal tightness doesn't just make intercourse more painful but can also lead to mental blockages where the woman, anticipating pain, is having a hard time relaxing or entering the arousal state. It's a vicious circle.

I find it such a dumb thing to promote the idea that tighter is better. A woman can have so many issues under such circumstances, from throwing pleasure out the window to dreading even the regular gynecological checkups!