You answered your own question.
Triple H is trying to change the mindset of an entire company on many things including size. He's fighting an uphill battle and has to convince the execs around him including Vince that he's right. NXT is his platform to do it and it has taken time to work to being able to present a limited series like this.
Except its a creative issue. What economic argument is there today that a smaller wrestler is less of a draw than a big one?
You telling me that WWE can't make money off anyone? Look at how long they are pushing somebody like Roman despite him not being ready for the spot and now even when he is in it he is getting booed.
Is Bruan and Big Show selling more merch than anyone else?
The execs care about the the economics and the size is a creative and personal taste issue that probably only 4 people in the company truly believe in.
Steph Curry is the biggest star in basketball right now. He is a sub 200lb NBA player who isn't 6'8" or 6'10" like Lebron or Durant. In the Vince McMahon world Robin Lopez is the biggest draw in the NBA.
UFC just had a record year off the backs of 135 lb women and 145 lb men under 5'10".
Messi is 5'7", Serena Williams is 5'9",Tom Cruise is 5'7", Cristiano Ronaldo is 6'1" and sub 180 lbs, and Pac and Floyd drew the biggest PPV ever.
Neither in entertainment nor Sports height or size is not the determining factor on making money.
Otherwise Hafþór Björnsson, Paul White, and Rich Piania would be the biggest stars.