1. adding qilins and prowlers to Blackwater vehicle pool will suck, it will have a higher chance to get that and everyone would prefer to get a armed vehicle over them, hence why the hunter,strider,ifrit, and 50 cal. were removed since you could already buy them (thanks @ThatNerdyGuy)
2. One of the reasons qilins/prowlers were requested to be removed were because of how OP they actually are, it isnt the easiest to shoot someone out of a qilin/prowler and their armor protection is really high it was practically a cheaper Ifrit with a little less protection.
3. With Qilins/Prowlers being removed that caused Ifrits,Hunters, and Striders to be pulled a LOT more. There aren't many armored vehicles so it was either those or hatchbacks.
4. Removing Qilins/Prowlers brought back some old strats to cartels such as pushing with box trucks. Having a limit on how many qilins/prowlers you could have was never the issue, when they were around there were very few vehicles on cap cause all people had to do is load 2 people per qilin or less and they had great protection+you could shoot out of it.
5. When qilins/prowlers were still around the APD had a MASSIVE advantage from what they have now. If people try and do dome strat, they block both entrances with cars imagine having qilins blocking them instead because the qilins were about the only ground vehicle the APD used and occasionally hatchbacks.
I thought it was a retarded idea to remove the qilins/prowlers when it first happened, but now i realize that its a lot better without them. You can actually shoot someone out of their vehicle no problem, fighting cartels people would only push with them instead of loading up ifrits, etc. Removing qilins actually opened up a lot more opportunities for other vehicles and a whole new meta to fighting cartels, etc. People used to put qilins that are bulletproof and you can't shoot thru in certain areas to protect them. I personally have a decent amount of warpoints and a lot of people do as well so I wouldn't really care if a qilin/prowler got chopped I would just spend more warpoints on another one. If anything qilins ruined Cartels when they existed (IMO). That is my 2 sense on it