For me it is about having something new and different. Frankly the big stuff may fly well - but in a way that makes it too easy. It is more challenging to make something small that performs well. Martin Lambert's "10" size turbine prototype
https://www.youtube.com/watch?v=X4DeRX7q1w4 is more exciting to me than any 1/3 scale yawnmaker.
All thngs being equal a smaller model is a bigger technical challenge, going big is a copout.