Two notes on your rant:
First, no redhead has ever been cast as MJ in a professional capacity. It's not that it's hard, it's just not important to anyone.
More importantly, good guys do finish last. Good guys don't finish the way "bad boys" eventually have to. They keep going. This does mean that they can eventually have the proverbial "hot girl who doesn't have time for nice guys," but that usually comes after that woman has been hurt enough that they're willing to try something new. They are not won over by geekiness, they are turned off from their previous type by extended bouts of emotional and sometimes physical abuse. This is the entire point of the Liz Allan character in comics, and I suspect will remain true here. Mary Jane is deeper than that. She's not just a prize, and while she should be very attractive, the iconic moment for her character is "Face it Tiger." The point of MJ in the comics that we all love is that MJ being attractive is a surprise. That she's already into Peter, not won over by him. MJ is not the unattainable girl. She's definitely not Penny. Liz Allan is Penny.
MJ is something different, and based on the comics, and not Big Bang Theory, they'll get a lot closer to that "Jackpot" moment than they would if they listened to rants like these.