I might agree with that if I hadn't discovered over the past several weeks just how hard it is to get someone to play a Plebeian. Considering for a good thirty plus years IC, Plebeians were literally painted as absolutely inferior in every conceivable way, uneducated, unfed, worthless slaves, the stigma is probably understandable. Caelisolans aren't really much better, other than the wings not being useless (slightly higher strength overall), but there's less of the social - and for that matter OOC - stigma surrounding them. From the religious stance, it's about removing something "impure" and, really, embarrassing from the Elysian genome - alien blood. Alien species being inferior, their souls are also inferior. Not a fate an Elysian deserves.
From a socio-political standpoint, the existence of S18 and S20 seraph means Plebeians need to move into more educated and higher-ranking ends of society. Plebeians as an impure hybrid species have a major social handicap, and aren't likely to be accepted by older patricians in higher places, even under a moderate government. So something has to be done on that end.
Back to the OOC aspect of the argument, which is where the complaint is. Compare, for example, to the
Yamataian species, which is significantly more "perfect" but was also used to help remove an OOC stigma.
...one that didn't really even have a reason to exist, considering Geshrin were already probably more invulnerable than a Caelisolan. Elysians still get sick, still need to exercise, still can only fly in minority cases, still have sharp cultural divides, still have a remarkable division in their upper politics between tradition and liberalization.