They're not (Windows) PCs though, where much of the apps you mention are ported for free because the user base is so vast. Nokia are almost certainly funding the ports of these apps themselves, as there is little in it for Opera to port their browser, or Adobe to port Flash. Nokia need these applications in order to sell the devices, the software vendors aren't doing out of the goodness of their hearts.

The economics of the Internet Tablet is very different to a normal computer, and application upgrades being produced into the future is not going to happen while it still costs Nokia to put those upgrades on the device. They can only justify such an expense when there is a reasonable business case for doing so, and with the 770 that business case is now very weak. Eventually the same may happen to the N800 if it ends up being incompatible with the successor product and/or the closed source licensing deals are per device.