I’m pretty sure none of these things are a major influence on the faction imbalance. In Classic, for example, PvE servers are overwhelmingly Alliance dominated, and PvP servers are overwhelmingly Horde dominated. The overwhelming majority of people who play Horde do so because they want to be the ‘bad boys’, and the overwhelming majority of people who play Alliance do so because they want to be the ‘good guys’.
Furthermore, I don’t concede that Alliance players have it particularly bad. In BfA, for example, Boralus is a much better designed city than Dazar’Alor, and Drustvar is usually considered to be the most interesting of the starting zones. And whilst I haven’t been a particular fan of the overall plot in BfA, particularly as it related to Sylvanas and the Horde, I did rather enjoy Jaina’s more personal story on my Alliance character(s).
Even as a new character, I think Alliance have better choices. I think Dun Morogh is the best Level 1 starting zone in the game. And whilst the human zones are less visually interesting, I still think Elwynn ==> Westfall ==> Redridge ==> Duskwood is the smoothest and easiest early-game levelling path.