Great question! Two reasons. One, I wanted to build something on my own from the ground up rather than contribute to an already established large project. For me, it's a better way to learn. Hopefully people find it cool and want to use it. But if the best that happens is it's just a fun project I built then that is just fine for me. Secondly, the data layouts are different. They are very similar in the single-file, graph db respect. But lattice is transactional and row oriented while kuzu is columnar.

Kuzu appears to be a retired effort.