
Spoilers : I've read till chapter 30ish, when he becomes the blonde regas. Some comments really didn't pass the vibe check.
Didn't the ML get abused precisely because people were scared of his eyes? Like yalls really hating on MC's new appearance when ML got abused cause of his appearance. I just wish people could see MC for more than just his buff body.
The MC is super nice but not naive. His past actions influenced people to protect the defenceless young prince, and even after he reincarnated he is still strong-willed. He respects the body he took over and did an actual burial to grieve for him. I love him so much.

I think it's mostly disapointment. I don't think they actually mind the body change but more like his previous body was somewhat uncommon so it was refreshing. Then they learn he will change body to the VERY overused twink and will probably take the "uke" role (even if it does lose in proper meaning in a Shonen-ai) so the dynamique between them will follow all the common troop attached to such couple (heteronormative).
So peoples who didn't really paid attention to the cover just discovered that no, it's just temporary and this story will most likely follow all the regular troop we already get on daily basis when they were excited for something new. It's not like he couldn't be in a regular body or even in another beefy one, the author choose this for the contraste I think.
Myself I was less hyped when I found out but not to the point to drop it because like said, it still seems to be nice story. But it's just a bit of a shame. ^^

Of course, the disappointment is totally valid especially if people didn't look at the cover or read the summary. Everyone has their own aesthetic preferences.
Just pointing out those extreme comments bashing on the blonde regas's appearances when there's so much more to the MC's personality. He don't suddenly become a damsel in distress just because he got into a frail body.
It's fine to simp over the characters and drop it if it's not to your taste, but this isn't a R-18 webtoon(at least not yet). It's a heartwarming story of a neglected prince finding someone who truly loves him, and I hope people give it a try despite the numerous hate comments here.

As for the reasoning why the new appearance is like that, it was established very early on that MC is a unique regas, and all Regas other than him looks the same-blonde, pretty face. That's the reason why he was chosen to become the prince's regas in the first place, because he didn't look like a typical regas.
Yes, the author could've chosen to reincarnate him into a totally normal human with the same build, but then the title of the webtoon wouldn't be "Regas" anymore.

I actually agree, like the plot was really good and interesting, and people would be dropping the story just because of a dumb reason, i mean i do like buff uke but be for real you would drop a story, a decent and actually good story for that reason, this days you can't even find a decent story, so you should all just be greatfull
And he's still the same person just with different body like y'all actually being haters right now

Regas seems to be "trained" rather than being "born" this way. You can see that with the other disciple that didn't choose to be a Regas. It was just custumary to choose young beautiful male to "seduce" the dragon. I mean it's pretty obvious that the meaning of being a Regas has been lost with time.
So no, being in a regular body when he reincarnated wouldn't go against the story by the setting made by author. They just choose that because either it's their preference. It's that the case it's fine. But the reason could be sadly that peoples are more "confortable" with a feminine "uke". I just hope it's the first case and author wasn't pushed to such standard. Either it's pointless to wander about that now. ^^
But I do think it would have been less awkward that this "transformation" waw revealed earlier like in some kind of Chap. 0 or a foreshadowing event in the beginning of Chap. 1. It will have been warn people to not get too attached to his current self.

Oh yes, I didn't say "born" but "look" because these Regas are expected to look a certain way, and MC is unique because his master picked him out despite the differences.(You see MC questioning whether he really is a Regas because he look so different)
The author will probably expand more on the Regas situation, it's the title afterall, but I think not everyone can become a regas, there should be some innate powers in them. If not, it wouldn't be a special position given to them. If you notice at the start, the person quelling the ancient dragon's rage is also a pretty blonde(and looking hella sus). I'm hoping that there's a history to all these.
*Spoiler zone*
Tbh don't mention a body change, I didn't even realise he was gonna die so it all came to me as a surprise, but I accepted it pretty quickly since the author made use of the "reincarnated into a villain body with a very good personality "troupe nicely. The body the MC reincarnated into is a typical spoilt Regas, and instead of standing out in terms of appearance now, he really stands out amongst the Regas for his personality, and it shows because his friends could recognise him despite his body change (not to mention there were a lot of Regas claiming to be his reincarnate after he passed away, so suspicions were on his head.) I quite like the emphasis that the ML is going to fall in love with his personality instead of his appearance.
Why are the comments all about how he became a "twink". The MC is still the same sweetheart, and they are in love your honour.(btw if anyone is worried about the age difference, there's a timeskip before MC wakes up again so they'll be arnd the same age.)
I respect individual preferences but are yalls really dropping a good story just cause the MC changed bodies....