fwiw Elon promises "half" the ads, not just fewer. If Twitter increase the total number of ads, as you say, then the value proposition of this arguably goes up.

Regardless I think the problem is ads on a site like Twitter aren't really worth paying to skip. I have Spotify premium because it really is annoying to listen to an unskippable audio ad in the middle of a playlist, but scrolling past a promoted tweet is not much different than scrolling past a tweet by a follow that is about something I do not care about.