To me it all boils down to the needs of the individual. As said it just another tool. A lathe has a lot of potential but as with anything it takes time to learn how to use it.
For me at this point I have a huge stash of parts and kits. Being able to make more parts doesn't make sense for me, i want to use what i have. If you are starting out with a small stash and have the skills to draw and print parts then it might make sense when you look at what current kits cost rather than canabilize a bunch of kits to build one.