Dying in games can always be frustrating but it can be even more frustrating in team based games when your deaths are caused by a teammate's actions. The ability to skip the kill cam is a basic feature that most games have now and it will reduce the amount of rage quits and churn.
Additionally, during the respawn time you are unable to view the progress on your own ult. I think this would be good to view easily somewhere on the UI so a player can decide if it is fine to change characters. I often find myself waiting the full 15 seconds to respawn just to check what my ult charge is at and if it is a good time to change characters (obviously I wouldnt want to change from a DPS character to another DPS character if I have a full ult charge).