"Bottom line - free bundles should work just like bundles with products associated so that the flow is the same and the user experience (capture) is simplified."
I agree with this. I am segmenting my users before asking them to create their free account, so once they do, I want to associate a different free bundle with them so I can send them different email campaigns and show them different content based on their segmentation, even though they are all "free" members.
Second this. I think I'd like to see Products generalized to handle zero-value, that way every sign-up flow is the same for free and paid offerings, including one-click purchasing.
We tried for a long while to make this free bundle thing work and ultimately gave up, implemented a gravity-forms registration for our free events. We use shortcodes to show gravity forms to anyone who would qualify for the free "bundle", except now obviously, there's no free bundle. Between paid purchases and gravity forms, we're now looking for registrants in two places. =(
To an outsider, generalizing Products to allow zero value seems as simple as an "if" statement:
if (value > 0) call payment processor else don't
do everything else