I do not understand why blizzard is afraid of a ‘hide pants’ option in the first place.
It hiding pants would really be a problem in the first place, why not cover up our character’s lower bodies with long underpants? Or just not allow us to remove gear from the legs slot, but only allow us to replace it.
Just put in the damn ‘hide pants’ option, all this illogical jumping around obvious features that should be in are so incredibly stupid.
My guess is that within Blizz a debate similar to this happened and the hide top but not pants was the weird compromise that allowed it to go forward.
Given that hiding the top did not result in the game being shut down by the authorities, I think it is safe to say that letting folks run around in their bathing suits will leave the Republic standing.
Why this hasn’t been done a long time ago doesn’t make any sense.
neat stuff
Free the thighs.
Free them.
All of you asking for a hide pants options might be missing one factor: there are numerus “pants” options that amount to a loin cloth to bikini bottom, as long as these are around Blizzard will likely be either reluctant o not see the need to hide pants as you could not mog into one of those.
Just 2 examples, one is racial but both are cosmetic:
Tauren heritage pants
the Blood Troll subligar
Tauren only.
Includes a wrap with feathers around the leg.
Honestly they really should just stop being puritanical and let us hide pants…
and weapons while they’re at it.
And you kinda missed the point, which is with these options, and others, Blzzard is more likely to go: you have these other mog options, why do you need to hide your pants?
They are not being puritanical (if they were, those other options would not be around), they are being “you don’t need this option when we provide you with so many other options that have the same effect”.
If the issue is with certain robes/dresses, maybe ask for the dress/robe to take priority if it covers the full body, I.E. if it is one with a slit up the thigh, nothing that would be under the slit, save the leg, shows.
I have had similar issues with the holiday outfits, belts can be hidden but unless I choose the right pants/leg armor the look was ruined.
Why ask for something complicated when something simple will do?
Just adding a hide pant option would be much easier. 
At one point, even I was open to a hide pants option, with the stipulation that it would only be active if a chest piece that covered the full body was used as the mog/look. I’d even extend that to a look that would amount to a bathing suit (bikini) look I just expect Blizzard, in order to keep the teen rating, does not want to advertise that you can hide everything, so they would make it so you can hide top or bottom but not both so you have to get creative for the look you want.
Hiding pants wouldn’t up the rating though… any player can just take off their pants at any time they want, it doesn’t mean the rating goes up.
So just add the option Blizz, nobody would think you’re a degenerate company anymore than they already do.
Well, the lack of stats does. 
In combat… but while being in a city anyone can literally take their pants off and prance around.
The only inconvenient is that it’s something you gotta do manually and consciously.
Why?
You can be in just undies already. This won’t change anything. It will just make mogging easier.
Yeah. I think that’s going to be my new hobby. As a dwarf, I’ve got a poppin’ booty.
I genuinely do not get where this argument comes from. I can quite literally go run a key right now, hide everything, and take my pants off and put them in my bag. Does this suddenly make the game rated M? No. Are people asking to hide everything and go commando and have everything on full view like in Baldur’s Gate? No.
People are asking for an option to hide pants, and like I already said:
For what I am specifically highlighting, I’d be fine with Blizzard just making the pants disappear like it does already in the Trading Post which sends the message that these robes are meant to show a little leg. If we can’t have that though, then we should get hide pants.
Agee with OP. No hide pants option completely defeats the purpose of the aesthetic of the dress. I was really disappointed when I went to transmog this last night. I ended up scouring every page of pants I had to find something that would work. Fortunately I did, but like the OP there are parts of the pants/shorts that are still visible. Please fix this.
Likely for the idea of companies needing to protect themselves from idiots. I know it won’t change but I also know that if someone heard “you can hide all armor” and took that to mean “you can be nude/naked in game” (keep in mind, some might not realize that characters have underwear) they could demand the rating be raised or the game removed from shelves.
More or less, while I agree with the idea, I also see how the…less then mentally able of the general public would raise a fuss if there were not stipulations or whatever,
In essence, the ones asking for it an reasonable people would have zero issues, but to keep the lowest common denominator, as far as outfits, happy, they have to make sure there is nothing that can be taken the wrong way.
Some sort of nod to Aphrodite? Never heard of that toy 