You seem to assume that riding with gears is more fun, or easier, or more efficient, or something like that. If you believe that, fixie doesn't make any sense at all.
But in my experience, fixie is more fun. It's not easier, but it's not really harder either. It can be more of a challenge. It's more like a full contact sport somehow. Some routes are more fun on the fixie, others are not. So it makes sense to choose carefully.
+! especially the part about some routes being more fun! I've ridden 4 Cycle Oregons fixed. First two were very mountainous and hard, but, the routes had one or two hard climbs and fast descents each day. Not a lot of stopping and changing gears. (I was 59 years old for the first. Going to Crater Lake and down on just one gear wasn't going to happen.) My third Cycle Oregon fixed did some of two days on the Oregon coast highway. That was a nightmare. Hills, both up and down, way too long to be fun on just one gear but way too many to be stopping all time. Leg and crotch killer. I won't do that again.
I like that full contact sport analogy!
Ben