On my first install of MC15, I missed the auto-import message. On my second install, even though I knew to watch for it, I almost missed it -- a small message on a busy screen.
Aside from the time-wasting aspect, I think the big risk during MC15's beta phase is that MC15 will end up loading the same media files already being managed by MC14. This can mess up the unwary user and data.
For instance, if both MCs are pointing at the same media files, a database or file change in one MC won't be seen by the other MC. Imagine a user getting to know MC15 by doing a bunch of tagging work, but while still using MC14 as the "real" media manager (this is my situation). Make changes in MC15, then go back to MC14 -- none of the changes are there, because MC14 and MC15 must use different library files. Even if MC15 is set to store tag changes in the media files, MC14 won't know they are changed.
MC15 and MC15 must be separate environments because (it's been stated) the library files of MC15 and MC14, while having identical names, are not compatible. (I assume this means the .jmd files; what about .jvi files?). Also stated, an MC14 backup can be restored in MC15, but not vice versa. But since the library files are not shareable, and since using different MCs to manage the same set of media files is unwise, and since backup-restore is not two-way, when MC14 is already installed, it seems wrong for MC15 to default to auto-import of media files, thereby leading the user to possibly work in MC15 before the user is ready to leave MC14.
So maybe existence of MC14 should be checked as a condition of launching auto-import, and if found, not do auto-import. And/or, present a message such as this, and force the user to answer it:
Media Center 14 is also installed. Caution: To maintain data integrity you should manage your media files with only one version of Media Center. If you import them into MC15 you should stop using MC14. Do you want to automatically import your media files into Media Center 15 right now? (You can also import them by making a library backup in MC14 and loading that backup into MC15.)
It actually can be more complex because the library might not be Default or not at the default location (mine is neither). Also, the MC14 user might have set up multiple libraries, perhaps organized media by type, but auto-import doesn't know this so will grab everything into one library. Just because MC15 thinks it finds an empty Default library doesn't necessarily mean anything.
Unless I'm drastically misstating the issues, it's difficult to see a reason to have MC15 auto-launch import when MC14 already exists.
Just a suggestion....