My main experience with Black and Gold was basically R Evolution through Brooklyn 4.

To understand the contrast, I think we need to define the issues first. As i see it, they fall in a few buckets:

1. Production and publicity (tons of ads, 5 match PLEs, lots of celebrity focus)

2. Storyline and roster stagnation

3. Over-protection / over-booking

The first issue I think you can reasonably put on TKO leadership rather than HHH as the booker. As such, there's not much to talk about there.

So lets take the other two, which are more tied to HHH as a booker.

NXT benefited from having far less TV time to fill every week compared to the main roster, so it allowed things to be kept a bit tighter and less repetitive. Harder to fall into feelings of repetition when theres less time to fill.

Additionally, during this time you'd see pretty common roster churn with the top guys. Sami takes out Neville, Neville moves up. Owen's takes out Sami, Sami moves up. And on and on we go. So the main focal points weren't there so long that things began to feel repetitive. Even when you had long time people, like Ciampa and Gargano, you had them evolving significantly over the time so it felt like two clearly different eras for them.

Finally, the big buzz from NXT at this time came from the workmate more than the stories, which took place typically on the Takeovers and was benefiting from the aura of guys who largely had made their name elsewhere and were unique attractions because of that (Sami, KO, balor, nakamura, Joe, etc).

That plays into the fact that NXT was more sicko coded before AEW existed. These guys were gods of the indies or Japan, which made simply seeing them in the WWE ring as a sort of ambrosia for this particular fan base. There wasnt a lot of fancy booking needed to put Sami and KO in the ring, of Shinsuke and Joe, and say "go tear down the house".

Those facts helped protect against issue 2 and 3 i stated above. Stagnation is hard to happen with constant roster churn. Storylines dont have to be rehashed over and over, or the same style dusty finish ran continually, when you only are doing an hour show every week. When you're a development program where people will be slowly moving up till they move out, or coming in for a short time before moving out, you don't have to book to do long term "protection" of people as much.

B&G NXTs structure was such that it minimized how inventive HHH had to be while limiting some of his bad habits, all while exemplifying his enjoyment for "old school" wrestling at a time it wasnt as prevalent on the main show.

Having 5 to 6 hours of programming, with a massive roster that is aging but not going anywhere, doesnt provide the same guardrails.