The very first step in the update is a backup of the device.
If the user has been using the device as designed, contacts and calendars are synced to a supported application on the computer or a cloud service. Pictures and videos taken with the devices are copied off to a computer regularly. Media and apps should be in the iTunes library on the computer.
The only reason that someone would lose data during an update is frankly, due to failing to pay attention and not having a backup.
If you sync your device regularly, you have a backup.
The updates are not causing more and more problems, frankly you cannot take the postings in these forums as indicative of what every user experiences.
I have never experienced a problem with any iOS update and do not know anyone personally that has experienced issues.
My device was not backing up for some reason, so thank you, as I now know why items where going missing. However, with each update, album art goes missing or an album is scrambled and songs seporated, and I'm finding it very fustrating, as I'm quite OCD about the state of my iTunes. So thank you, but I stand by what I said, I'm quite content without the new updates as it seems to find an item to recategorise each time.