It's not really the burst potency that's the primary issue, although it's a contributing factor. The reason why everything moved towards resource systems is that timer-gated burst becomes more powerful as you have more downtime. PCT basically ignores this, starts with a full burst on opener without having to build up to it, and can use downtime windows with no target to build up motifs, which are the only long casts.

It's basically like if Soul Sow gave full gauge and had a 1 second shorter cast. That's not creativity, that's just unbalanced. If motifs required a target, you probably wouldn't need to make many tweaks to potency. But this was pointed out ages ago.