Why is it such an advanced thing? How hard would it be to create something that simply had a whole lot of inputs to even just one output?

The more inputs you add to a video device, the more the signal could be degraded by the electronics, so the more work that needs to be done to make sure signal degradation doesn't happen.

But the real reason is that there simply aren't a lot of consumers who own 14 video devices and need a switcher that big. So they just don't make devices with that many switches in the "consumer" level of features/quality. Once you start getting into the high numbers, their customers are all running pro setups, so they make them with the pro features and quality because that's what their customers need.