They have to cut ties with OS's eventually. No reason to cover 32 bit systems when they now have 7, 8.1, and 10 to support. It's easier to support 3 vs 5 (7-32, 7-64, 8.0-64, 8.1-64, 10-64)
Solidworks has announced for years that 2014 will be the last update to support 32 bit OS. This has a lot to do with the fact that 32 bit OS can only support 4GB RAM. So if you're still running a 32 bit OS it's time to upgrade anyway.