Weirdly in my location Burger King closed two locations (one of which seemed to be fairly successful) and both are being renovated into Wendys. Which kinda sucks, since BK has their okay-ish $6 meal, and Wendys seems to more be going the "Just a burger? Well, that'll be nine bucks." route. On the other hand, I'm pretty sure I once got food poisoning from the less successful BK, so... not sorry to see that one go.
Wendy's doesn't freeze their beef ever, so they believe it produces a better burger which probably drives up costs. I think your theory about "not just a burger" is correct.
I haven't been to a Wendy's in years. But I don't live near one. I think I like their frostys, and like that they serve potatoes even though i would probably order fries.