The OP makes several assumptions...
1. People have been asking for better designed adult pull-ups for years...
That may be voiced on this forum, but not by the general public. Most box stores have removed adult tabbed briefs from their shelves and only carry pull-ups. Most incontinence in the general public is stress type. So people are looking for the bare minimum of what will take care of their needs. Why wear a tabbed brief if a pull-up will do? Why wear a pull-up if a pad or guard will do? Why wear a thick pad or thick guard for minor drops? Manufacturing a better designed pull-up requires it to be profitable, and with the number of potential customers that may be difficult to accomplish.
2. They want the convenience of being able to simply pull it up and down with the higher absorbency of a typical adult diaper.
As evidenced on this forum, people can have a difficult time with sagging of tabbed diapers, even plastic backed, which are the best fitting of all types. Pull-ups sag horrendously, unless they happen to fit your body type and size perfectly. So it's not just an issue of adding more padding and SAP, but better design that stays up better. At the same time, most people complain about the granny panty appearance, which is caused by the higher waist to provide more elasticated material to hold the thing up.
3. I also heard that adult pull-ups were designed for females in mind. Every time I pee in a adult pull-up, it always leaks before I even finish peeing.
As stated, pull-ups are typically
made for lighter incontinence, not full on voids. That said, have you tried a high absorbency pull-up such as the NorthShore GoSupreme? It has a 38 oz. capacity. Compared to an average pull-up, the GoSupreme absorbent pad has a much higher rise, both front and back, and is much wider and thicker. It is not a very discreet pull-up. I know for a fact it can handle a heavy void. I still do not trust it the same as a MEGAMAX tabbed diaper, but they are different animals. And you may be able to tear it off, you will still need to remove your shoes and trousers to put another one on. That's why I carry tabbed diapers in my changing bag, never pull-ups. I'm fortunate that the medium fits very snug so that it stays up, even when wet. As an aside in comes in black as well as white.
The golden rule of manufacturing: delivery–quality–price, pick two. Also known as the unobtainable triangle. There is another aspect though–quantity.
In the disposable incontinence market delivery is always one of the two choices picked. If a customer can't get their preferred protection when needed, they have no brand loyalty.
Whether the choice is made for quality or price is determined by projected sales–quantity.
Large companies choose price over quality so as to manufacture the most widgets, thereby cornering the most market. Boutique companies choose quality over price to serve a niche market; gold widgets vs plastic widgets. And then there are companies that find a place between the the large corporations and small boutiques. This is called guerrilla marketing as it steals enough market share from the large companies for them to notice, but their large size makes it difficult to respond, while also drawing a small market share from boutique companies, because people want quality, but not the price.
In the incontinence market the large companies are evident. ABU, Tykables, Rearz, Bambino, and BetterDry are examples of boutique companies. And NorthShare is the great example of a guerrilla marketing company.
Disposable incontinence products are single use products. They have zero value in the mind of the end user. If you went to someone's house and they showed you their extensive collection of facial tissues and toilet paper, you would think they were crazy, because none of it has value. You blow your nose, wipe your ass, and throw it away. I'm incontinent, not ABDL, but I know that even for an AB or DL, once they wet a diaper, it has no value to them, it's going in the trash when it comes off, even if they had spent $100 for it. This is why companies think very carefully about what they are willing to invest into developing a new product.
All that said, I agree with the OP's enthusiasm for high quality products. Being incontinent, the improvement in products over the last three decades has made my life much easier. I hope @bigtoddler96
that you call Northshore and ask for samples of the GoSupreme pull-ups. They may not be everything you want in a pull-up, but they may make wearing pull-ups a little more enjoyable until a good design for you comes out.