as a customer, i don't have the choice to not pay for such upgrades but continue using the old one.
And yet, the SaaS subscription cost is charged continuously whether the customer likes the upgrades or not.
So no, i don't agree with the SaaS business model. It's more extractive. The point of buying a piece of software is the same as buying capital equipment - purchase once, and have it work "forever" (and since software doesn't rot like real equipment, this should be even more true).
What i would pay a subscription for is live/in-person support.