If the fans don't mind, if they continue to attend and watch games, and drive revenues ever higher, why should the owners care about doping? They shouldn't--they're businessmen, after all.
There's one interest group in baseball that has an obvious, direct self-interest in putting an end to doping: the players. If steroids and growth hormones cause long-term physical breakdown, it's the players who should have the strongest incentive to halt the arms race. And the extraordinarily powerful players union is ostensibly well-positioned to broker such an agreement were it not for the fact that the union focuses on maximizing earnings for individual players, rather than the union everyman. It might be sensible to argue that all big league players are better off due to the profits generated by the home runs of the last decade, but a lot of that additional revenue has accrued to a relatively small minority of players.
Indeed, how many unions allow its highest paid member to earn seventy times the amount of its lowest paid members?
In other words, the union is effective at leveraging power over the owners to garner larger shares of league revenues, but is ineffective at equitably distributing those revenues among its members. The union fails to distribute salaries evenly because revenues largely derive from the talents of the elite, not the average. Accordingly, the union is poorly positioned to broker a steroids agreement along utilitarian principles because that's not really its purpose, philosophically.
I think the players union might take action if the fans start turning away in large numbers, but that's unlikely to happen. Fans have known, or suspected, for years that some players take steroids. Perhaps we'll reach a tipping point and fans will turn to soccer, Tolstoy, or their Wiis, but in the meantime, attendance just continues to climb, which tells players to keep on doping until further notice.