It makes a lot of sense, particularly if you're going to replace a PC for lots of people. The default pointer on the PC was the mouse, on an iPad it's your finger. And that's plenty for most people. I've used a Wacom tablet for almost two decades because I've required more precision for graphic and illustration work. As usual, the applications on the iPad just need to catch up. I'm hopeful they will.
There really is no reason why the iPad, in time, shouldn't be able to replace a PC for almost everyone (not just "most"). What would be needed is A) for people to really figure out what their job is – not the series of tasks they perform or processes they follow, but their honest-to-goodness output and B) for software developers to make apps that are flexible enough or custom enough for people to get their output better.
Andreessen Horowitz analyst Benedict Evans has had some great thoughts on this. A strategist's job isn't to put together charts and graphs; there are dashboards that do that stuff now. Their job is to derive meaning from those dashboards. The thinking stuff, and there's no reason a tablet shouldn't be every bit as effective as a PC for that. If your job is to check people onto their flights, your job isn't to type a bunch of stuff in, it's to make sure people get to where they want to go. It feels like software developers are mostly making touch versions of legacy applications – software so large and broad that it optimizes on volume rather than being the best tool for the individual.
I feel like the missing piece is many more smaller teams of app development companies that are creating lower cost ad hoc tablet software for specific individual businesses – everything from food trucks to corner stores to teachers, shipment companies, hairdressers, etc. What's needed is to know PRECISELY what people need and to focus on the best UX for their outcome. Not so they feel busy or effective but so they actually are.
Maybe what's missing is something like hypercard so these businesses can get part of the way themselves without having to learn Swift.