I have to say I’m with @RayCaruso and @mvevitsis on this. I think I understand from an architecture standpoint that this approach makes rules simpler to interpret on the server side (and therefore faster and cheaper, which is good) but it does so at a significant cost to developer accessibility.
Of course, rules are only a small part of the platform and thankfully actual SmartApps are not this hideous. But getting rules to work still matters, and the poor readability of using JSON for this will result in bugs that would otherwise be easy to avoid. Hell, it looks like it already has - even after preconditions were fixed, for months now the built-in official automation tool in the app still doesn’t work consistently if you use location modes in conjunction with presence conditions in a “when any condition below is met” rule.
If SmartThings own developers can’t implement rules this way without bugs creeping in, what hope do the rest of have?