I think a subscription business model is the only honest way to sell software that will require ongoing support. If you're comfortable with a snapshot w/o updates, then by all means buy once, but I think coming to terms with the demands of ongoing support also means coming to terms with continuing to support the product in some way.
That said, I wish there were more variations in the way to pay - a long term license with a high upfront fee and a low monthly, an immediate access option with a high montly and no up-front fee, etc.