Alright, I'll ask the the what, to me, is the much more obvious solution to round this out (having just been browsing the Controller sets and considering my options regarding containment).
Isn't the more optimal choice here simply to include slows and/or some other hinders in the effects Containment applies against?
To my mind, it still checks all the boxes?
It is still conditional, and meaningfully different from Dominators capabilities.
It either allows it to be conditionally effective at top tiers as well as through levelling or the existing compensations would still apply for Incarnate AVs
It properly balances out the value of the inherent across Controller powersets that more crowd control options beyond the specifics currently listed (i.e. Holds, Sleeps, Disorients and Immobilizes specifically; Stuns and Slows I always thought were curiously absent in the description)
It's readily understandable and supports multiple playstyles with that understanding without it automatically invalidating the 'Control' motif and, being conditional, doesn't just make Controllers "Blaster Plus!"
More than willing to accept I'm missing something here as I get re-acclimated into CoH. It does seem to me that control powers do not draw on this inherent consistently enough (the disparities seem pretty significant in a quick review) but I'd not want to lose either the flavour or opportunity for team based capitalizations on how it works now. I'd rather just expand the list of control-based qualifiers.
This is assuming it _is_ an item that would benefit from an improvement, of course. I think a bit more range would be appealing, but I'm not going to claim to be the expert on the implications there.