Ocarina of Time had Link obtain a Pass from its Gerudo chief, after rescuing all four carpenters (and thus sneaking by all the sentries, and defeating the four cell guards), which allowed him to enter the Gerudo Fortress normally from that point onwards.As for the Cross-dressing to enter Gerudo Town, I'm sure that's meant mostly as a way to disguise Link so that he can sneak in without getting attacked on the spot, Plus, he isn't required to do that anytime after the Gerudo quests are done with.
Why couldn't Riju give Link a similar pass?
As for the "sexism" angle, it'd be one thing if the Gerudo didn't allow any other races (male or female) to enter, and were isolationist, which was seemingly the case in Ocarina of Time - it's a whole other kettle-o-fish to allow only females of the other races in.
And, uh, the Gorons; are there any female Gorons in BotW? Are the two or so Gorons in Gerudo Town females? Because if they're guys, then how come they allow them in but no other dudes? Fucking hypocrites.
Sure, you no longer need to enter that godforsaken den of misandry after doing all the quests there and getting the Korok Seeds in the vicinity, but you still need to crossdress to enter it, no matter what.
Oh, and why the fuck does their word for male sound like "foe", or in other words "enemy"? Bloody chauvinistic bigots. Absolutely, despicably appalling work there, Nintendo.