Bad takeoff performance does not mean a bad airframe. Takeoff performance and things like global warming (fuel efficiency) are often inversely related. No aircraft is perfect at all things. The big wings needed for shorter takeoff during a Nevada summer can mean more drag at altitude. Boeing builds for average customer conditions, not just the special case that is Vegas. (Altitude+heat+dry air = low air density = need bigger wings, bigger engines, and/or longer takeoff roll.)*

*There is probably some room here for a joke about how people leave Vegas heavier than they were when they landed.