> I've seen customers fall into the trap of thinking they don't need expensive developers because you can drag and drop, just people who can use a mouse can crack on with NiFi.

That is sort of the key problem I see with NiFi (and equivalents). The heavy emphasis on graphical UI and visual paradigm sort of implies that its oriented towards non-developers, but problem is that it doesn't make non-developers suddenly expert system architects or developers even if they manage to click through the UI. And many developers probably prefer just defining stuff in code instead of having fancy UIs. So it sort of falls between these to categories.

Of course there is huge spectrum of skill in people, and there are probably plenty of "semi-technical" persons to whom this is perfect match, especially if supported by some more techy people.