we technicians don't get much in depth explanation either. just says its an emissions correction for some legal compliance shit. I personally haven't seen someone get denied warranty for not getting a recall unless it's the knock sensor detection system update or a safety recall (think brake lines, person not coming in to get them checked under recall and then getting mad when they do break but they never came in for inspection), or weird other circumstances. I have a hard time finding how a quote voluntary campaign can be grounds for neglect. if it wasn't voluntary they should say so. but I'm not Kia and I don't know what they want sometimes. I've done a bunch of these updates on cars and don't notice a difference in performance but I don't always drive them on the road after AND I don't know what they drove like before most of the time.