Winrate isn't the reason people don't play xeno. Its because xenos are no name antags that have to listen to retards who turn queen on and have no idea what they are doing. You cant have friends as xeno because you don't know anyone. That shit doesn't build communities and teams it builds mercenaries who don't give a shit about each other.
Buffing xenos actually has the opposite effect of making xenos more fun because the only fun thing about xenos is challenge. When xenos are too strong they become boring as fuck.
I had more fun playing as a researcher and kicking it with a bunch of friends when research update happened than I have EVER had as xeno. Xeno is only fun for personal accolades. If I see my friend getting killed as a marine I will go try to save him, if I see my xeno team mate getting killed I assume hes a fucking retard and gonna get me killed if I go try to help him. The devs think xeno identification would create elitism but no identification creates toxicity. Its why xenos fight with each other over the stupidest little things because theres no consequences to your actions and no one will ever know who you are.