I believe the answer is a combination of components, not just a single part. Yes, smallmouth fight harder, but largemouth do fight hard, just for a shorter period of time. Depending on the lake, they will also put on a acrobatic display, not to the extent of a smallmouth, but one nonetheless. So you aren't comparing a 10 to a 0, rather a 10 to a 7.
As far as prettier fish, that is in the eye of the beholder. I find the lighter colored largemouth to be better looking than any smallmouth, but I also prefer brunettes over blondes. When they get larger, smallmouth lose their proportions, their head is too small for the rest of their body. The head on a largemouth grows with the rest of him, so one that reaches lunker size doesn't look like some weird Picasso type fish.
Wild rivers are indeed beautiful, but on the west coast, they are rare and if they do exist, have trout instead of bass. So like the average looking girl who will go to the prom with you, just being available counts for something. That also plays into being catchable, smallmouth are notorious for being here today, gone tomorrow. You can't catch what isn't there. One of the reason why sunfish and catfish are popular than Musky is you can catch the former while the latter wears you out for just one bite.
I agree that fighting ability is more important than size, that is one of the reasons I prefer catching a 1 lb bass over a 2 lb trout. However, when that size changes the fight, it needs to be accounted for as well. I inadvertently hook catfish over the 15 lbs every year and they fight like the dickens. However, after about 10 minutes of them pulling my boat around and taking drag, I just want to land them, check them out & move on. Catching a fish is a date, not a relationship.
I'll end this with something I wrote to another poster who felt like you. A 5 lb smallmouth jumping 2 feet in the air will take your breath away. However, the first time you see an 8lb largemouth break the surface with his big ol' bucket-head and thrash about, mouth open, I guarantee a "Holy S***!!" will come out of your mouth, even if it is a Sunday and you just got back from church.