No-one would have known or most not cared if the dresses had been off the peg - in fact it would be sounds of it been easier and a better results if they had.
Only reason anyone looking now at bridesmaid dresses is because Harry made a thing about it.
MIL and I actually though Meghan's wedding dress was off the peg - it's only when it was made clear it really wasn't that we though much about it. It was a minor detail on the day - she still looked lovely - but I've seen articles written later blaming fabric for the poor fit so I'm bemused at posters saying it fitted well and rest of us are all misremembering.
Meghan was clearly let down with the dresses. I'm surprised she appears not to have had more help with the wedding or that when she was clearly upset Harry didn't ensure she got some more- but I think Harry putting this anecdote in the book is a pattern of trying to throw shade at his family and trying to look as if he's keeping his hands clean at same time- this time it is 3 year old niece and 3 week post both SIL.
I think people who come out looking bad are Givenchy and Harry for being a petty jealous man.
I also don't agree white tights or sock or even the foot tights that with most shoes won't be seen would be usual in a UK wedding - but I'm also getting impression tights may have subtly different meaning in US or LA.