Business doesn't work that way. You make hay when the sun shines.
And there are cases when you can't charge. Because of things your competitors are doing.
In a restaurant they don't charge you for napkins and water although they could. (Actually they do charge for premium water but that's a fairly recent invention).
The idea of business is to make money.
It's not up to anyone to decide how much profit is "enough" for comcast to make. If they could simply charge more per month without games they would.
Sometimes it's easy sometimes it's hard.
Take airlines. They would like to charge you more for a ticket but if they do you might not book the ticket. Better to be able to advertise a cheap price plus extras than an all inclusive price without extras. Why? Because people are not rational buyers (generally) who can figure in all the things and the "total cost of ownership" as they say with cars.
"doesn't that seem a little bit like they might be playing on peoples lac of knowledge of the systems involved?"
Well of course they are. But so what?
There are many times when companies take features out of a product just so they can make different tiers and charge premiums.
Take web hosting. Take companies who sell people extra disk space that they will never use and don't know they don't even need at all. There are many examples of this in business.