[austenallred]

I disagree with others making the conflict of interest argument. I don't see how it would create a conflict of interest if they applied a hands-off, self-serve (call it laissez-faire if you must) advertising strategy -- in fact this would create much less of a conflict of interest than accepting direct donors.

But that point is moot. The true risk you run is alienating contributors. The beautiy of Wikipedia is that they have (almost) completely eliminated the influence that Wikipedia itself has on the content. It set up the rules and lets the crowd do the work, and lets the crowd be incentivized by the contribution it is making to society, like most other crowd sourced projects. It has created (or is striving to create) an autonomous encyclopedia.

If Wikipedia were to have ads, even if it weren't a for-profit company, it feels like contributors should receive something in return, a la BleacherReport.

Bottom line: It's not about conflict of interest, if Wikipedia accepts advertising it starts to feel like a business, and the incentive of contributors to keep contributing is greatly lessened.