Nonsense. Paid interstate travel is a form of interstate commerce, and hence subject to regulation by Congress. About a dozen or so Supreme Court cases affirm this fact. Our right to interestate travel, like many other rights (eg. the right to bear arms), are subject to regulation. So long as the regulation continues to allow all citizens who wish to do so to travel accross state lines, there is no violation of the right. In this case, all citizens can easily get a passport, so requiring a passport for interstate travel does not violate your rights any more than requiring a state-issued ID.
That passport can easily be abused to control aperson's movements.
Not any more than a driver's liscence or other state government issued ID, which are currently required on all domestic flights.
My proposal is very rational. Passports are easy to get, difficult to forge, and easy to keep track of. The same is not true of drivers liscences. Therefore it is irrational to have state-issued drivers' liscences, which come in 50 different varieties, be the standard ID. It is far more rational to have a single, easily monitored, and difficult to forge standard national ID, such as a passport.
You claim that having a passport be the standard id would reduce our freedom. You have yet to support this assertion with a single rational argument.
Actually, they aren't really required. It's just much easier if you do use them.