During what must have been the Dapper release cycle, not many scientific applications had these fancy menu entries. Instead, after you installed a science package, you'd probably find yourself poking around in a Terminal trying to work out which command would launch the application.
I think I provided around 40 new .desktop files, in addition to the substantial amount that several others contributed. Many of these are now in Debian (thanks mostly to Barry deFreese). It was a great feeling to see the scientific applications I had installed appear, one-by-one, in the Applications menu as time went by.
I'm pleased to say that the good work has obviously continued, and it's great to see how many applications now have good, sensible menu entries.
This may not seem like an Earth-shattering new feature, and indeed it isn't. But it does mean that people can now access a large collection of new, useful applications more easily than ever before, rather than being put off by not being able to find the application they just installed!