… errr, yes? It's extremely hard to shoehorn the electronics and battery needed for an entirely new cellular networking technology into a smaller package. Miniaturization was, for the longest time, a process that entailed a big premium in consumer electronics products (think SONY Walkman and point-and-shoot cameras, for instance).
These gigantic, battery-draining screens on smartphones are a bit of an historical anomaly that come from people's obsession with using them for, well, all kinds of tasks, and if you look at other product categories, miniaturization or thinness is still the norm. Yes, even in the PC world, albeit not to the obsessive extent Apple's industrial design team takes it.