Because the manual transmission changes the entire experience of driving it, whereas a manual choke or ignition only changes starting it.

Some people (including myself) just find it more enjoyable to drive a manual. I feel more connected to the car, like its doing exactly what I want it to, and I feel like I've done something when I've driven home rev matching gears perfectly.

It's just about preference at the end of the day, but I do find manuals more fun.