Your point is stronger than you probably think: there are entire countries where ad-supported smartphone apps are the only really viable way of communicating for the majority of people because things like normal phone calls or text messages are ridiculously expensive for the locals. The business of financing communications through ads is actually helping millions of people in these affected poorer countries.
That's just my personal observation. Make of that what you will.
Removing the possibility of financing phones and calls through ads changes the entire market dynamic. I can’t say for sure that the ad-free prices wouldn’t drop because they were suddenly the only option available and scale gains (or a survival need) would drive costs down.
Companies won’t lower their prices if they don’t have to, but they will go to great lengths to survive…
That's just my personal observation. Make of that what you will.