This seems like a very reasonable decision on Microsoft's part: they make it easier / legal / quick to test on their platform and more people will support and develop on it.
For example, I know a few online banking solutions that are IE-only. The most you need there might be a certificate, so resetting the vm every 30 days isn't such a big deal.
I try to keep the VMs as small as possible anyhow and if you need data, you keep it in a VM shared folder that you map in the Windows guest.
I mean, if you want a fully functional pirated version that doesn't expire every 30 days and you never have to activate you don't exactly have to look very hard, or far.
You can just roll back to that snapshot at the end of your 30 days and everything will continue to be usable.
Which is basically the only reason I do have an old Windows XP vm on my Mac.