It really does solve a lot of problems, especially due to the segmentation Canon used being annoying: my 7D has 5 slots for lens corrections, but the M bodies only have 3. So if you're a JPEG shooter that enjoyed straight lines being straight, you could only bring 3 lenses or had to lug along a laptop so you could use EOS utility to swap out the corrections.
You can also map the progress in processing power through the corrections, at first it was just vignetting correction in stills, then vignetting and distortion in stills, followed by DLO. Around the time Digic 8 came along movie mode could do corrections and with Digic X the camera can do everything both in stills and video.
As for being part of the protocol, I suspect Canon reserved a few "ask lens for data" options in the protocol and started implementing specific functions for that much, much later. Like the ability to update the lens firmware from the body in 2012!