Jimmy Wales wrote:
Will the Wikimedia Foundation ever accept money to change the content of the articles? Not as long as I'm alive, ok? Anyone who thinks otherwise should check their premises and remember who I am and what I'm doing and how I spend my life.
Forgive my scepticism, but if we start accepting advertising and become reliant on it, it isn't unknown for the company who is advertising to pull their adverts, cutting Wikimedia's revenue.
A possibly apocryphal story is of a program on the BBC, I believe it was a car review program, who gave a bad review to a certain American car model. The CEO of the company found out about it, was furious and ordered the advertising team to pull all adverts to punish the TV station. The advertising team replied "sorry sir, but the BBC don't run adverts".
A lack of adverts is one of the reasons why Wikipedia can be neutral. If we become reliant on others for our existence, they can exert influence over our content. I don't want to see us go down that route.
Chris