while Blueprints are very nice and intuitive, I found them far than ideal for programmers when experimenting new solutions. I think that support for a “traditional” (= with source code) scripting language would allows quicker iterations than using BPs or starting immediately with a C++ implementation.
- it should be usable everywhere a BP is allowed;
- it should allows for quick iterations (no editor re-launch, no long compile times, etc.);
- integrated editor with supports for autocompletion (at least for UE4’s objects and types).
- (a 1:1 mapping to BPs would be a nice extra feature).
Of course, all the above from a programmer point of view