Having recently updated to the latest version of the beta for two droids, I can certainly understand why it's not available in the Market as a generic Android product. My wife's update installed flawlessly, no more complex than the previous versions.
On the other hand, my Droid I required at least a dozen efforts to install the software, even when I attempted to follow the intricate instructions very carefully. I eventually managed to install Swype, but only after multiple reboots not documented in the instructions and removal of my "Apps 2 SD" app.
Suffice to say that for many phones the simple "uninstall-the-previous-version-install-the-new-version" approach was only the start of nightmare.
What it amounts to is that Swype is not designed to installed to an already operating device (even unrooted). It's designed to be installed with the operating system in a "virgin" device. Once installed, it leaves traces of itself all over the file system that are very difficult to eliminate. The problem seems to have been exacerbated by the 2.2 version of Android.
The folks at Swype have always said that their business model is aimed at OEM's, not end user consumers. And while they've done their best to make it possible for members of their beta community to continue to use their software, I can certainly understand why they would not put the software into the Market. It is simply not designed to be installed from that source.