The whole "Kirito getting bigger" storyline is pretty obvious, it's clearly meant to be a contrast to Inoda. "It feels like it can rival Inoda-kun's size now..."
The intention is to highlight that Asuna isn't all about size, it's not a case of "the bigger, the better," but rather about physical compatibility.
This is evident in the dialogue with Inoda where he's "hitting all the right spots inside."
The author had already mentioned that Asuna wouldn't get with any other guy, so he had to come up with this temporary enlargement for Kirito to make that point. And let's not forget the emotional aspect, the author wanted to emphasize that Asuna isn't just a woman who's all about size, she's not easily swayed by Inoda.
The reason she's drawn to him is a combination of sympathy, empathy, and great physical compatibility. Even if a BBC with an even bigger size were to show up in the future, Asuna wouldn't be NTRed again just because of his size.
Your points are logical, but I ask myself, is it really necessary at this point? Asuna (and the player) is aware that Inoda is a sex god, has a huge dick, exceptional stamina, orgasm control of a tantra master and always hits her g-spot. Do we really need further evidence? Should Asuna and Inoda go to a doctor in the next update so that he can tell them he's never seen such matching genitals, and all people on Earth should instantly kill themselves, allowing this celestial couple to reproduce the world's population with its perfect genes?
The more I think about Part 2, the more I doubt it's going to end well. It's such a mess: Kirito's new brain implantation and sexual awakening, magical dick growth medicine, and divine interference in the real world, plus Inoda turning from a scumbag into a good guy. Let him undergo cosmetic surgery, buy a membership for the gym, and he would basically be Kirito from the anime in a few weeks.
PS: I see no reason why the dick growth arc couldn't have been done in FOG; that would be way less questionable, as it's a virtual world with magic. Even growing additional dicks wouldn't be as illogical as magic in real life. ^^
IDK, I probably give up on thinking and just enjoy the scenes.
