We've discussed these in the past, so please excuse me for repeating myself ...
The NEC has required that there be a 'disconnecting means' at each fixture for a few years now. The industry has taken this to requirement to be met by the use of the little snap-connectors you describe.
I'm delighted that we're seeing new fixtures with the disconnects already in them. Beyond that, the idea has been a fiasco.
Why? Primarily because there is no common connector in use. The ones that come with the fixture are not what you will use with the replacement ballast. So, you're right back to working hot, working in the dark, or having an awful daisy-chain of connectors in the fixture.
IMO, the issue would be resolved were ONE ballast manufacturer supply the connector with every ballast, be it OEM or replacement. Such a move would simply push all the rejected designs into the history books. I'm referring to Advance here, which is very much dominant in their industry.
A less likely approach is for there to be a NEMA-standard design for all to meet.
