Apologies if this is crass, but from my experience working as a digital artist and taking on commissions from literally just anyone and everyone who wants one (Typically furries. As they say, sex sells and it's a huge part of that community).
Men are 100% getting off on writing these reviews and publicising that they're wearing women's underwear. It gives them sexual excitement.
It's thrilling to them exposing what secret thing they're into, and they get a kick out of it.
They intentionally toe the line between just acceptable enough to be excusable as "Oh they're just reviewing a product" or in the case of art commissions "Oh they're just telling you what they want for their art piece".
That's where the thrill is, it's in toeing the line of what's acceptable and getting away with it, if that makes sense?
I've repeatedly had people commission me, and it's been extremely obvious that they're getting off on even just the process of commissioning the art because they get to talk about it to, essentially, a stranger, and a female one at that!
Something that should take me a week maximum will take me over 2 months because they're dragging it out as much as possible, nit-picking over tiny details again and again, always over genitalia, so they can specifically keep talking about the bit their getting off on.
It's only ever men who do this, female commissioners even those who want sexually explicit art, NEVER go into as much detail as the men do.
Despite this, male friends will tell me I'm overreacting and that the client is just being clear about what they want, ignoring the fact that details being described would not be visible to even need discussing in the first place.
You can review underwear like these without directly referring to the fact that you're male, or that it can "Adequately fit" their package.
Perhaps the world of art commissions has tainted me, but that very much to me at least reads as either "My package is large and it fits in these panties" so a brag about dick size and a statement about size of underwear to mask the brag.
Or alternatively it reads as "My package is small and it fits in these panties", so an attempt at self humiliation, as that's a common trope in that fetish subculture.
It gives off humiliation, sissy porn vibes.
It's akin to low level flashing to me to be honest, or that fetish subculture of men who purposely wear no underwear and specific types of clothing to accentuated and "show off" their bulge.
The thrill is that people are noticing, looking, seeing, reading, the thrill is that they did not consent to participate in that exchange, they're just a bystander really.
It's low level exhibitionism and I don't really think that's appropriate for a pace like M&S.
Leave those types of reviews to Love Honey and Anne Summers where they can be as crude as they like and no one will bat an eye imo.