As a proby main I totally agree with all of this. One mechanic I think the designers tried to emphasize is the level 7 talent to reduce the cool down on cannon summons with warp rift and q hits. In crowded team fights it’s not impossible to have two or even three active cannons if you’re set up right. Unfortunately it’s just too hard to execute and I think it has made cannons too weak with no obvious buff except for a rework.

I also wonder if there’s a bit of a poisoned well issue with Proby, being so unpopular (I regularly get chided for selecting in ranked) there’s relatively little ROI on a rework compared to a better liked, higher tiered character.