Nothing wrong with a little walking(running) the bike once in a while - it's good 'cross training.
Glad it works for you. I'd be in hell with a single speed. I used no less than twelve of my gears on my ride today, and being able to tweak for the terrain, my state (i.e. mitigate my suffering), etc. Maybe if I were young, small and wiry, but I'm an old Clydesdale with bad knees.
Also, I ride with other folks, so the 'do my own thing' isn't as social. It's definitely an interesting, personal, ascetic take on mountain biking. Your bike is still a work of art.