too expensive. square and the like make sense from the point that you already have a phone, and it's more peer-to-peer payments than a commercial solution.
Square is badass but it doesn't offer simple menu capabilities such as modifiers. Restaurants have fairly particular needs in terms of data structures. Also, doesn't Square only support personal accounts at this time and has specific weekly transaction limits based on a credit check?
Additionally, Square can't control cash drawers, etc, and if you take in a lot of cash (restaurants often do), you need a place to put it and a way to correlate it at the end of the night.
But seriously, Square has the most beautiful iPad app/control panel, and for the most part it is very intuitive to use.
No offense, but that may be the most abstract sentence on Earth. Certainly it is possible that they could write some software, possibly taking the form of a plugin architecture, to store menu modifiers (options and choices), and that it would likely be on their server, for download and use by their client app during customer menu creation. It is also possible that they could move to reading RFID cards, or form a softball league. So many possibilities.