All web traffic should be encrypted, regardless of purpose. This increases the work that nation-state level adversaries must do to effectively spy on the population. And it's cheap and easy to do these days.
Fair enough. I don't think this is a "shady" practice either. But I think it's an old, out-dated practice to charge extra money for a feature that should be on by default.
BUT! the point here is the op claims this is a shady practice to provide https to their paying customers.
A shady practice is if they take your personal information and sell it to another without telling you. Shady is when companies lie to their customers.
And this situation is not.