This is one of the key points. You can plug an iPhone into almost any modern PC, Apple or otherwise, and download the photos and videos. But you can't do the same for other types of data without using one or more of an Apple computer, specialist software or iCloud. The middle option, which is the only one not entirely controlled by Apple itself, has a long history of attempts that proved not to work entirely reliably or last for long. And as you say, for an iPad, where perhaps more users want to do substantial creative work, the same issues apply.

I understand that Apple's current business model is heavily tied to locking customers into its ecosystem, but that does become a significant problem for people who just want a nice phone but also respect for their privacy, and I do think Apple should be called out for this just as I think it's fair to praise them for being much better on broader privacy issues than most of their competitors.

Many third party apps that have a sync feature only work with iCloud, so a lot of people are forced to use it.

It's worth noting that nothing in iOS or iCloud prevents apps from encrypting data using a separate user key and then storing in iCloud. (Essentially, using iCloud only as a reliable substrate for syncing files it cannot read.)

That popular apps do not do this is likely due to lack of demand as much as anything. I am sure there are some content creation apps that do provide this functionality, if one is willing to search hard enough.