I agree with the need to diversify our revenue streams over the long run, and I think I agree with the sentiment that we should not 'leave money on the table'. However, some of the discussion around directory tiles makes me uneasy. (I think the worst thing about the whole thing has been how badly the idea was communicated, but that has been pretty well established, so I won't beat that horse any further. Personally, I don't think any revenue from the idea would be significant because, aiui, only new users will see the ads and then at most nine times, which if I were a company, I wouldn't pay for. But I don't know anything about such things and there are plenty of people at Mozilla who DO know about this stuff, so I'll believe it could make money somehow).
My position only makes sense if you assume that advertising is bad per se. I do. I know many people do not, especially in the technology sector. But I think advertising is a bane of modern civilisation - not just on the internet, but in magazines, on billboards, on public transport, in sport; it is poison. It is particularly insidious in that we don't realise we are seeing and being influenced by advertising, in part by design and in part because of its ubiquity. In the rare times I have spent time away from it (the subway in Prague a decade ago, hiking in the mountains) returning to a world full of advertising feels as jarring and unpleasant as it ought to. I would love to live in a world where we paid for websites and software. If I could pay 1/10th of a cent for every page I viewed and if Mozilla could be funded by administering that and taking 1/10th of a percent of it, then I would be very happy indeed. Unfortunately, people on the whole seem to prefer free, and so it is a dream.
The argument I dislike is 'we already send search traffic to Google in exchange for cold, hard cash, and Google in turn makes money by showing these people ads; therefore, showing our users ads directly in the browser is no different or no worse or something'. As a software engineer, I know that indirection is very, very important. It is totally incorrect to treat a value the same way as a pointer to a value, and I believe the analogy holds with monetisation too. It comes down to incentives - money is a very powerful incentive (not the only one, and I trust Mozilla more than pretty much any other organisation to balance other incentives, but it is still an incentive - we each want to keep getting paid to keep doing these awesome jobs we have).
So, with the current system, in order to maximise search traffic and thus income, we might tweak our design to make the search box more prominent or otherwise encourage more users to search via the search box (I believe that this is not quite the case because we do not get paid _per search_, i.e., there is some slack in the system, and I don't think we have ever done something like this or intend to). That is not so bad, I would not feel bad about encouraging people to search the internet - it is kind of an essential task. Now Google (or whoever we might sell search traffic to in the future) is incentivised to show their users more ads, but there is no incentive for us to modify the browser to show the user more ads.
With directory tiles (or any system where we are directly showing ads to users) the above does not hold. The monetary incentive is to show users more ads and more often. And that (in my opinion) makes for a worse user experience.
In summary, when the incentive is indirect, optimising for it does not negatively affect our users. When the incentive is direct, optimising for it does negatively impact our users. And that makes me very uneasy about going down that road.
However, I fear we might have to. We need money to fund our mission for a better web and the current situation may not last forever (maybe it will, and we can all live happily ever after, but I fear everything changes). Fortunately, I trust Mozilla better than anyone to ignore the incentive described above, I just wish we didn't have to ignore it.