Indeed, it should be a preference - this is (nearly) 2019, we shouldn't have to be creating plain text files and popping them into configuration folders that are normally hidden deep inside your Library folder!

I don't mind change if it's for the better, but the most annoying part of it is that Illustrator CC 2019 and InDesign CC 2019 both currently use the old method to scale proportionately (hold down shift) and Photoshop uses the reverse. If you're switching between the 3 applications, it's impossible to remember how the scale proportionately - I've wasted so much time this week un-doing amends because I just can't get to grips with it.

Adobe, if you're going to change a common action that people have been using for, in my case, over 25 years, at least either do it consistently across the suite of applications or not at all. I get that there are separate teams working on each application, but something fundamental  like this should be shared among all the developers at a higher level.

For my sanity, please make it a tick-box in Preferences that you can easily disable to revert it to the legacy way of working!

Thank you!