Just as a point of order. You offer no case for Pulumi and your one actual discussion of the semantics is misplaced as it deals with if expressions, not statements. Stratified ifs that occur at the non-recursive areas of the language are usually not a problem for these change management systems.
I'm not offering a case for or against either, to be clear - and neither are you - indeed you went so far as to say effectively you wouldn't even bother considering the semantics since they _must_ be awful.
The semantics of the Pulumi runtime are probably fine, but the semantics of the DSL layer that preceeds that when mixed with the sensible semantics of the Pulumi runtime are a recipe for disaster. This is based on my extensive experience with declarative DSLs in imperative languages. The impedance mismatch is high. Nothing to do with Pulumi's internal state management, but it's beholden to javascript.
> Why should I care about writing 'new' in front of all my declarative configuration?
Because that’s how your choice of language instantiates an object. Try F# or Swift or Go if it’s that annoying to you.
> What happens when an if statement depends on a concrete value?
What do you think “count = var.concrete_value ? 1 : 0” is doing in Terraform, exactly?
> The leakiness of the abstraction is too terrible to even consider.
While you are are entitled to your opinion, I’d suggest you are very much mistaken, and would implore you to actually consider it for a minute.