NetworkManager and ConnMan (Dan Williams' Blog)

You created a throw away program that fits the needs of ONE Linux user, targeted at ONE specific piece of hardware. Now take that program you wrote and make it fulfill the needs of every single Linux user, with every possible piece of hardware, and wanting to do everything possible inside the Linux kernel with their network, using one application and then maybe you have done something noteworthy.

Currently, this application does not exist and it probably never completely will.

My point being NM may not work right out of the box on every computer, but it works on most computers rather well, which is somewhat of an accomplishment in itself. Dan William's does an outstanding job of fixing bugs that are reported to him and if you joined the network manager mailing list and took the time to post your debug logs, I am sure you would find that either a. your bug has already been fixed upstream or b. someone on the list would help to fix it.