I've always had the feeling that Blizzard regretted the bonus roll system and were working to phase it and out and, as of Shadowlands, they have. Think about it. Each xpac has reduced the system even more. In MoP you got 3 per week but as soon as a new tier came out you could infinitely farm the older ones. In WoD they only had two of them and you still can't farm the second one. Legion had a single bonus roll across all content. Then BFA knocks it down to 2 per week hard, with no bonus sources like from table missions. You could tell they wanted it gone.