Version difference -- index_lms.html vs. story.html for tincan

I have seen some posts on this, but nothing quite reflects what I have seen:

I was using Storyline 3 version 3.6.18134.0, always publishing for Tin Can, and I recently started getting messages about needing Flash, etc.  I realized that I had a pretty old version, so I upgraded to 3.11.23355.0.  The old version always defaulted to story.html for the launch url on the LMS Reporting screen.  The new version defaults to index_lms.html.

We go to our database to determine where the file should be, and it took me a while to realize what was going on and why nothing was being tracked.

So I changed the launch url to be story.html (so I wouldn't have to change the database records), figuring that would fix things, but it did not.  The published output is the same, and it seems like putting story.html in the launch url made no difference.  The only way I can get this to work is to change our database to point to index_lms.html

This in itself is not that big a deal, except that I will now have to remember to change old database entries when a story is updated.  My main question goes to understanding what is going on.  Why does the launch url make no difference?  Why must I now point to index_lms.html no matter what?

Thanks