I kind of understand where tegleg is coming from, as I ended up inventing a lot of low-level stuff myself. For example Slate is good, as far as C++ UI frameworks go, but most base widgets lack so much functionality that I ended up with custom classes for buttons or drop-down menus. But that we could even do it, with clean C++, in a way that works really well with the engine, is the other side of that coin. Having access to the full source code, having access to C++ to extend functionality, being able to make something that wasn’t envisioned by the UE team, can be worth it.
It really depends on your game, your team, and what you’re looking for. I don’t think UE is the engine for small projects, game jams, etc. It’s a really great engine for long-term projects.