by offering <50 email accounts for free, Google essentially destroyed the market for any other startups or companies to come into the market and offer non-enterprise B2B email services... thus limiting competition and innovation.
One could argue that the removal of the free tier at this point is simply because they've created an entrenched position, but one could also suggest that this creates a modicum of opportunity for another player to try to enter this space.
Certainly until today the $ size of the addressable market in the small business email space was practically $0 given Google's position.
[discuss :)]