Am I the only one who doesn't feel like Twitter is hammering me with ads? OTOH I don't use Twitter very much and when I do it's almost exclusively on my phone or iPad.
But I think the subtext here isn't so much that Twitter is hammering people with ads, so much as that their need to show users ads is causing them to constrict the marketplace for Twitter applications --- anything that might get in the way of an ad-supported strategy is, in this understanding of Twitter, in jeopardy.
I don't think the concern is that they've gone ad-crazy to date, it's that going ad-crazy appears to be the direction they're moving in going forward. Hence the need to push out third-party clients -- for ads to work, they need the only portal you view Twitter through to be owned by Twitter. (A third party can just strip out the ads.)