I don't blame Valve for not wanting to be 'the company that sold my innocent little boy a porn game'. Remember Hot Coffee?
But the primary demographic for videogames hasn't been kids for a long time.
San Andreas was rated M, and that didn't stop the media from flipping their collective shit.
Part of the digital distribution medium even allows Valve to deliberately hide content based on user age groups. With a few more account level controls they could easily implement parental filtering. There's no reason for Valve to continue to block games like this from entering their service, esp. if they are leaving it to the Steam community to determine the quality of the game or lack thereof.
Because a 13 year old kid could NEVER find a way around age restrictions. :eyeroll:
And while they may be leaving it to the community to determine the quality, that says nothing about the suitability of the product for the Steam catalogue.
I'm not suggesting the lassiez-faire fuckfest that is the Android marketplace, where every third app is a nude picture screensaver for 1.99, but there should be a point of entry for visual novels and dating sims on the service, esp. considering that it's the primary digital distribution platform for videogames. I would love to see a project like Katawa Shoujo make it onto Steam, but with the rules set up the way they are it could never happen.
In the end, Steam is a retail distribution service. While their fundamental operating model differs from brick and mortar stores, just like those brick and mortar stores, they have to maintain a certain level of decorum, lest they risk a shitstorm of concerned parents and family advocacy groups. While the actual amount of influence those groups may have is laughable, all it will take is one kid getting a porn game from Steam, and the media will jump all over it. Again, I sincerely doubt Valve wants to be making headlines for CORRUPTING OUR NATION'S YOUTH.
Anyway, I really don't see how this is is a big deal. Valve isn't saying "don't make porn games". They're just saying "don't put porn games on Steam". Lack of Steam presence has not, nor will it ever stop people from making, distributing, acquiring, and playing porn games.
EDIT: An official response from Valve, found on Kotaku, of all places:
"Steam has never been a leading destination for erotic material," Valve's chief spokesperson Doug Lombardi told Kotaku. "Greenlight doesn't aim to change that."