That's what he has Yahoo's executives for, right? In a big company you need not one, but many voices/advocates of different disciplines. His role is important, because else they end up with a steaming pile of marketing gags with no awesome product to make up for them. I would also not call Ad-Driven/Freemium/Subscription mode "features and experience". Yes, this can make or break the user experience - well if it would, then David would stop them.
You can't argue it both ways. He either still has power over what the suits come up with for revenue, and thus hasn't actually abdicated any responsibilities at all (just given some biz dev guys a little more autonomy) or he has given up those responsibilities and the day the suits press forward with an experience-damaging move he doesn't like, he will discover he doesn't actually have full control over his product's features/experience.
e.g. if they say "tumblr's going freemium" the follow-on questions of "how do we differentiate the experience of free vs paid and how do we communicate the value of the upgrade?" are experience questions that need to be answered and designed in a holistic and considered manner. [1]
[1] And that's why I say those modes are absolutely part of 'features and experience'. Flickr just switched between two fairly-similar freemium models and we power-geeks had a hundreds of comments debate over whether the experience/value jived with the offering and/or was communicated cleanly.
