Not all apps are restricted.
"Now I wonder how the people that wrote the apps feel about apple giving away their liecense? Sure you paid for a licesen for one device, but you didn't pay to use it on as many as you like. Thats called Piracy? Or maybe iPad owners will throw away their iPod or iPhone?"
Well, no, that's no the way iTunes licensing works. Unless specifically restricted anything you buy through iTunes is licensed against the account and the account can be registered for use on up to five machines at any one time (*not* five devices). Each of those computers can sync a number of devices (I don't know if there is a limit, but I haven't encountered one) and transfer any compatable stuff to the device.
So, you can own an iPod, iPhone and iPad and sync all of them with one machine (or each with seperate machines using the same account) and use all movies, TV programmes, applications, etc. with whichever devices support them.
So, *no*, this would not be piracy.
"Oh, and lets not forget, as every one seem to be doing.... that any one with a PC also has a library of apps and media they can use on a windows slate..... pirated or not..."
But that *would* be piracy (well, breach of licensing terms anyway) unless the license for the software specifically allows the use on more than one machine, which most commercial PC software does not allow by default in my experience. Granted, in practice most manufacturers don't make any serious attempt to restrict you from doing that and probably wouldn't persue you anyway, but if you're going to suggest that one system has an advantage over another you probably want to make sure which way around they are first.
That said, you appear to have missed my point anyway, here it is in a plainer form:
Apple make money from every sale though the iTunes store (apps, movies, music, etc.). People who buy the iPad will almost certainly already have an iPod and/or an iPhone, so may well not purchase as much content for the iPad as they will already own it, thus reducing the after-sale revenue stream.
It's a bit like the VHS->DVD->Bluray thing. When people moved from VHS to DVD they bought DVD copies of stuff they already owned on VHS, but it's unlikely they will buy Bluray copies of anything they already own on DVD. If the hardware manufacturers were getting a cut of every disc sold you can bet your life that either they wouldn't be compatable or the hardware would be more expensive (probably both, in fact).