Well I love Blueprint and C++. Now I have the option of programming in the language of the engine or a more visual Blueprint option. Coming from a background scripting in Torque Script I have many times asked my self why not programming directly in C++ when Torque Script is C like in syntax already.
I do understand that some people wish to have their own favorite language as an option as much have been invested in learning a new language. Perhaps giving Blueprint and C++ a might change your minds?
Originally I started out hating Blueprint but now I utterly love setup. So many options and so much flexibility. Strong visual scripting and still able to be so close to the source with C++. By using Blueprint I am able to work much faster and I can still use my programming skills making systems for doors, footsteps etc. that checks for Boolean variables and then hook them up against triggers which contribute to the quality of game play experience.
In the beginning I would say that Blueprint is not programming but as I use it more and more now I must say that it is still programming just a more visual style.
Give it a and be surprised.
That said then I think a C# option could be a good alternative for some people. You have the source codes so hooking it up should be possible.