Google apps itself has provided 7-year-old free services Gmail, Calendar, Docs, and file storage for businesses. You still can sign up for free as individual or paying a few bucks if you sign up as business account. Stopping free Google apps service could mean that Google would improve the apps for better functionality that might lead to increasing the productivity of its users.
Here is Google explanation behind its action.
When we launched the premium business version we kept our free, basic version as well. Both businesses and individuals signed up for this version, but time has shown that in practice, the experience isn’t quite right for either group. Businesses quickly outgrow the basic version and want things like 24/7 customer support and larger inboxes. Similarly, consumers often have to wait to get new features while we make them business-ready. (Google)