There are a lot of good points there Colin, I might move this to its own topic though, because I imagine lots of people will have an opinion on this.
In fact many of you will be eligible for free developer accounts through the University program:
Given the recent announcement of Swift Playgrounds, the proliferation of iPads in schools and Apple finally embracing open code I wouldn’t be surprised to see a similar initiative for high schools in the not too distant future.
You can legitimately side-load apps for a while now:
You can charge for your app! 
Anyway, you make good points, but if anything I think that Thunkable for iOS will make developing for iPhone more accessible than it currently is and allow a huge amount of people to learn iOS development that wouldn’t have had the chance before. Personally I think it’s a step in the right direction. Roll on beta testing!!