CC being in play more often makes the game predicable. That's what makes the current meta game constant burst attempts off stuns/silences with burst that takes little set up. It also means that CC in general takes a lot less thought and is not punished as much if it happens to go wrong, because you will have another chance to do it in just 10-15seconds.
Old PVP doesn't strike me as predicable compared to stormblood pvp. When you watch a samurai in the current game what do you expect from them other than a dash into a midari? Then rinse and repeat until you are successful? With the way jobs were in the past being able to potentially get a kill on their own with the right circumstances, you had a lot more variety in how a game could unfold.
I don't see the problem with carrying in solo play. If you think a person deserves to be dragged down by their teammates by purposefully reducing the number of actions they have access to then I find that strange. In a game with a healthy population this wouldn't necessarily be a issue. You would have plats with plats, diamonds with diamonds, high diamonds with other high diamonds etc. So artificially lowering people's ability to play better and making everyone the same is just a cheap fix to a problem it shouldn't have to fix. Fix player participation by making better PVP modes and offering more incentive to play with rewards for the average player.
Objectively speaking lowering the number of actions has not even helped participation. Rival Wings has been dead for a long time and in retrospect Rival Wings has died due to the game being so simple that everyone literally just plays healer. Rivals Wings not being pvp but a resource collection game.
Honestly I don't know why you would suggest adding 2 abilities per expansion, why not suggest what you think should be a hard cap on the number of abilities and have them just do it immediately upon expansion release? I personally believe 20-25 + 2 additionals is fair.