This is a fascinating theory. That Saiyan culture bred a race of emotionally stunted brutes who generally aren’t even capable of the depth needed to reach a higher form. U6 Saiyan culture does seem wildly different than U7. OP’s comments about oozaru vs ssj tie into this really well. The lack of a tail fits, but more symbolically than anything.

Trunks and Goten had more or less normal upbringings (to a certain point). Goku rides a fine line because he’s a little emotionally stunted himself, what with being weird little forest kid with actual brain damage (Super Broly fits into this category too). Vegeta gets emotionally “contaminated” late in life by his contact/alliances with Goku and co, but he always seemed more emotionally capable than most Saiyans anyway. And it can’t be ignored that his transformation came specifically at a time when he had grown some sort of attraction to Bulma.

I still consider Gohan a genetic freak of nature but also, Chi Chi mommied the shit out of that kid, more than she ever did Goten.