I read a lot of opinions on whether it is a good idea and it all boiled down to ‘my god, no, don’t write your engine. That said, I did and I am sure glad I did invest 3 years on a framework I know like the back of my hands’ and that told me exactly what I wanted to hear.
It’s like the whole AI debacle, really. If your goal is to ship a product, go with a premade engine. If your goal is to enjoy the craft and learn how stuff works, and you got that itch to do it the difficult way, then roll your sleeves and dive in. It’s always a pleasure to play a game with a completely unique feel.