evolutionary objectives are not rational. Nor are they particularly up-to-date, especially sugar cravings. Addictions, vices and impulses of many kinds are not at all rational, and it is a virtue to have the willpower to resist them.
> (1) what people didn't yet know existed
This is far from the only objective, and the substance of many ads demonstrates this: why do brands like coca-cola pay top-dollar for superbowl ad time? You would think they are well known enough..
> (2) what everyone else knows
Ads are not knowledge, it is common cultural reference for the purpose of advertisement. I don't see the value in this if you are not an advertiser.
> Ads work by and large because people want the products that the ads are selling
If we follow the same logic, no one would object to ad blockers, b/c the people who want to see ads wouldn't use them.
> People wouldn't need to be subjected to ads if it was desirable
Substantial value from ads is they communicate (1) what people didn't yet know existed and (2) what everyone else knows (because they saw the ad too).
Ads work by and large because people want the products that the ads are selling. A lot of ads are stupid and I'd personally rather not see them - but if I think that, they also probably aren't targeted at me.