You forget that SSL provides two benefits, not one.
1. No one can intercept the communication and read the messages. No one cares for driver updates so yep you would be perfectly safe letting everyone on your network read the driver files.
2. It proves that you are talking to who you think you are talking to. This is the bit you miss - for important system files that are executable, it's kinda important to make sure you get them from the legitimate source.
As it stands if you go to a coffee shop, anyone else there could tell your computer that there is a critical driver update coming from a malware server and your computer would happily download it.