How is it viable for ENWorld to produce adventures for multiple editions with small profit margins and a limited audience? They're even printing both editions.
It's precisely
because ENWorld is a smaller publisher that they can do this.
I know that seems counter-intuitive, but it's true. Morrus and co. don't have to turn nearly the sort of profit on any given book that a large company does. If they do much more than break even, well, I'm sure they'd
like to do better, but that's still technically a success.
Depending on lots and lots of variables, certain small RPG companies can sell a couple thousand copies of a given book (sometimes even less), and call it at least a modest success. The larger companies? Have to sell orders of magnitude better than that.
A company like WotC, or even Paizo? There's a lot more riding on their products. They survive based on the products they sell. They have a lot more in the way of overhead costs. They have more people on staff who have to be paid, and more bills that have to be paid off. With a company like WotC, it's not just a question of "Will book X sell?" It's a question of "Will book X sell better or worse than book Y? There's only room in the production schedule for one."
So it's not enough to say "An adventure made for 3E and 4E might sell." You have to show that it will sell better than an adventure made for 3E
or 4E alone. Furthermore, it can't just sell a
little better; it has to sell a
lot better, to make up for the additional costs of producing a larger/more complicated book. And of course, there mere fact that it
is more expensive is going to dramatically lessen the potential market, because again, lots of people aren't willing to pay extra for a book where half the mechanics aren't useful for them.
Plus, there's the fact that adventures are used, in part, to drive sales of the core line. WotC isn't selling 3E core books. Therefore, adventures that encourage people to play more 3E do them less good than adventures that encourage people to play more 4E--even if they sell just as well. (The same would be true in reverse, for Paizo.)
It seems like WOTC and Paizo are willfully ignoring huge demographics they could easily sell products to if pride weren't such an issue
Pride is pretty much
zero of an issue in this instance. Do you really believe that either company would hesitate to do this if they thought it was worthwhile?
Especially with the economy the way it is?
Don't let the flame wars fool you. The WotC folks and the Paizo folks aren't enemies. Their companies aren't trying to destroy each other. Neither of them wants to see the other edition fail, or the people who work on them put out of work. Heck, WotC has a corporate responsibility, for Pete's sake. Sure, they can still make bad decisions, but if this was anywhere near the no-brainer you seem to think it is, they'd have
gladly jumped on it.