That surge is delayed engagement after a full stop? Yup, common. I thought you were attributing that to the DCT. In fact, it is the hydraulic clutch connecting the ICE to the rest of the drivetrain. As far as I know, the DCT (electrically activated, not hydraulic) spends 95% of the time fully engaged in a gear and is only in neutral between reverse and first. This is different from regular ICE only cars that have a DCT. There, the engagement between first and neutral is what gets the car going. The Niro attempts initial movement in EV and then brings in the ICE. Any clutch feathering is done by the hydraulic clutch but the car is already in gear.
It is this common delay that is upsetting for most when trying to cross or turn in traffic. Some compensate by putting the car in Sport mode for faster response to throttle, I compensate by starting my turn or cross a half second early. Any surge should be happening because you pressed the throttle farther that you would have if there had not been a delay. I can only imagine that this might happen in stop and go traffic where a surge could potentially cause a fender bender. A lighter foot will keep you in EV and be better for safety and mpg in such traffic. I've never experienced that sort of unwanted surge, perhaps because I keep egg shells under my throttle.
Not sure why the Hyundai/Kia engineers designed this delay. I assume that it is a feature (perhaps protecting some part of the power transmission, or efficiency), not a glitch. Because this car has done this from day one back in 2016. I read on the Ioniq forum that there was a mid 2017 software update that helped, but did not eliminate it.
In another note, Ioniq owners are getting an update now to improve braking. Tesla also did one recently after complaints from consumer reports about inconsistent 60-0 times. In my Niro, there is what appears to be a dangerous glitch in panic braking holding a bit longer than the pedal is depressed. I've never experienced that in another car. Disconcerting to do this in traffic and want to release when the car behind you appear unable to stop in time. Hopefully this update addresses that but that is an issue I haven't seen reported anywhere so it may not be addressed. Kind of amazing that a software update improves braking!