In regards to downloading apps and updates, yes, I think it’s time to open up the restriction. It’s dtupid that I cannot download apps that are only a few hundred megabytes while on the go.
As for iCloud backup,however, maybe there’s a good reason. A corrupted iCloud backup can be a nightmare for users and tech support. Backing up via unstable connectivity like cellular might be the consideration Apple thought not to allow it, to avoid risking corruption. Remember that iPhones used to require to be tethered with a USB cable to be backed up via iTunes. It’s not until quite some time that Apple allowed backing up via WiFi, and that even still resulted in problems for many people.