Blueprint follows a pretty strict procedural design, but it executes it quite well. It's easy to imagine Blueprint's design used essentially to write something like vanilla C (without support for preprocessor).
I don't see how the inclusion of support functions and classes for engine interaction implies that Blueprint's language design is "sure-as-hell" high-level, per se, but in practice you're right that its design case is pretty high level.
This isn't exactly ment for Programmers, but level designers going one step further. Besides that, it offers accessibility that is very immediate. The visuals can provide a direct feedback of the signals processed (may the movement in the background not be random), relating the properties of the signal to other signs than textual symbols (e.g. to show a color's hue just dye the slider).