Not even getting into attractiveness being subjective, but Peebee is far from ugly. Like with Ryder, the animations are causing her to look odd.
I genuinely find her distinctly ugly, I was referring to her as Fugly the Asari before they revealed her name infact, and she's only gotten worse looking since the reveals given the visual downgrades and greater exposed of the amateur quality animations and cut scene direction. Not that any of the Asari look particularly good in this instalment, which is baffling given that they're a species designed to be the 'hot blue alien space babes' from their very conception, and that attractiveness is the basis for every characteristic they're meant to have.
Infact I'd say this isn't even a matter of deliberately aiming for unconventional beauty or diversity, all the main cast look various levels of inhuman, with badly implemented 3D models of uninspired, generic character designs. Sure, they look less ugly then the NPC's, but that's because those NPC's are all uncanny valley, hit randomise on the character generator and call it a day levels of awful.
I'd also say this is a step back from the diversity and more varied character designs of earlier games that managed to avoid the stereotypical unrealistically perfect looks so many games characters end up having. Even their body designs seem to have all been homogenised down to the same generic skinny blandness for the humans, and generic armour but with more details and less emphasis on non humanoid features for the aliens.
They're ugly and boring because, like pretty much everything that isn't combat we've seen so far for this game, the characters were clearly not given enough time, skill or basic thought at the conception stage to be any better. They look rushed and as if someone just said 'that'll do' once some basic checklist of minimum criteria was met.
I mean even fucking Tali managed to be more beautiful than Peebee, and we never actually saw her face, as well as her having completely inhuman limbs, but despite that she had enough character, presence and thought put into her design that that didn't matter. Meanwhile the new romanceable Asari keeps being quite rightly compared to Shrek, has no clear personality beyond general unspecific 'quirkiness', moves like a possessed mannequin, and has the kind of outfit you'd expect of a random background NPC in the previous games.
Seriously, the least ugly characters I've seen so far are the Turians and Krogam, and that's entirely down to having too few human characteristics to be immediately noticeable as fuck ugly.