Bolded the only useful parts about my coffee rant.
Reading between the lines he kinda hints that Vans design and quality isn't there. He likes foam midsoles and even for Cups Vans' approach is to make the most minimal midsole and just stuff a fatty insole in. He seems concerned with foam density because low density foams like that in Pop Cush don't last and pack out. It's not that Vans doesn't understand this, they just don't want to do anything about it. It's much easier/cheaper for them to not have to pour in or mold foam in and constantly reuse the same soles. Tiago has said he wanted a foam that lasted a long time and it does just that. Vans just makes a shoe aesthetically different for the most part then plops some generic foam in.
If anything they probably don't have enough market demand to need to do this. They're propped up by their really good/sticky rubber and selling the vast majority of their shoes to people who don't skate and don't care.
For me personally I have liked my Vans skate line and Waffle Cup shoes aside from the insole. Popcush is better now than it was, but it still packs out and the shoes get noticeably sloppier over their life. I like the Crockett high in it's first couple weeks, but every pair I've had ends up with an upper about as floppy as a Cons and while the heel protection is slightly better than a Half Cab, if I land too hard heel side or have to jump away from something and just land on my heel weird, my whopping 165lbs will bottom out the insole and heel bruise.
On that note I kinda don't buy it that he just wanted to try Vans shoes. He knows enough people to get test pairs for free and realize they didn't work for him before signing the contract. My completely hypothetical guess is that he found parts of the shoes great and was hoping to have the ear of design and be able to produce something more akin to his liking, but in the end Vans doesn't need to spend the time and money to do that and weren't going to.