It's supposed to be. They want SS to basically be exclusively for situations where you *NEED* your dots on a target ticking at full power immediately. IE rapid target swapping in arena and high priority adds in pve. The idea is for it to be a major dps loss in the long term at the benefit of a massive dps gain in the short term.
The issue is it really isn't for any dot but agony. Because agony needs to stack, of course swapping one already at cap is much higher burst. But you're looking at 2 gcds for ua/corr, compared to the TWO GCDS FOR SS.