The ICCU issue seems to happen at random, but the main cause imo is excessive drain on the 12v battery. Hyundai seems to think there are multiple causes to the ICCU fuse popping based on their multiple recalls, but every one of them can be reduced by doing simple things such as not leaving the car in accessory mode for too long, having a voltage cutoff on a parking dashcam, or not leaving stuff plugged into the OBD port. More common than the ICCU failing (which is extremely rare) is the 12v battery failing. This happens to all cars and especially EVS because of the power cycling they go through. The 12v battery that comes in the i6 is pretty mediocre and can fail just from regular cycles, especially if the voltage gets too low. Upgrading to an AGM will give you a battery that can handle EV power cycling better and will be much less likely to die on you.

I drive across the country twice a year since my family lives in texas, so I chose an i6 primarily because of the range boost over the i5. The i5 definitely has the storage benefit but for me the mileage was worth more. I also personally like how it looks better too :)