The thing about the Byleth trailer was it was clearly meant to also be a fake-out trailer, but when whatever plans they had shifted and it was put into a Smash presentation, it lost the element of surprise.
Not saying that would've spared Byleth from getting lit up, just that the trailer obviously wasn't shown in the context it was originally conceived to be.
i'll summeris it in the way you summarized pyra and mythras reveal trialer
byleth
byleth in smash
byleth is swordsman
byleth lose's match
byleth is SwordsWOMen which
byleth is axe, spear bow women
byleth win's the match with a crusty png as their ultimate attack.
honestly that text would've been the trailer
cutting back and forth from FETH in game engine, smash bros and the anime style cutscense were really messy, and there really didn't need to be a separate reveal for female byleth.
even if it was a surprise trailer it wouldn't work because by the time the surprise where's off the gameplay hasn't even started. and when it does it lasts for like 8 seconds before going back to another minute long segment that shouldn't have existed.
plus the jokes were terrible "there are so many Anime Swordsman so instead im gonna turn into an anime swordswomen!!""clever girl"
that was the awkwardest thing, and it had no impact, the screen just faded to black and in the meantime byleth became a girl so she wouldn't have to be bullied about being a swordsman.
for reference
funny part is since they made the haha we have sooooooooooooooo much swords's people joke, they added 3 people who use a sword.
Edit: seriously it's actually hard to watch this trailer
gameplay starts at 1:37, ends at 1:58. then starts again at 2:56 and end's again at 3:43 so there a total of 2 minutes and 49 seconds of cutscenes and around 1 minute and 8 seconds of gameplay.
Are you guys conflating the character reception with the trailer? Because Byleth's trailer is... fine. It's not the best one, but I don't think it's the worst either. It makes the sword-fighter joke, which I enjoyed.
byleth is my 4th favourite character in the game but it takes ages to get gameplay since the pacing is so slow, and once you get gameplay they go right back to the awkward shot's.