Do you think this show would be as popular had the Mane Six been Male?

[Unlikeable Pony 2,699]

Nah, definitely not. The show sells to little girls due to the feminine side of things, and adult fans tend to like it either for its cuteness, or (for more action oriented fans) its magical girl aspect.

You can't do cute nearly as well with male characters (usually) as girls, ruining the former reason, and action shows featuring males tend to be HEAVILY different from magical girl style action after all. So if you made the characters male, it would most probably not rely on affirming friendship to destroy the villain but would instead most probably default to outright physically defeating them.