Business Speculation:
Alot of the 'Same pricing in retail and on steam' is due to the game publisher.. if they want to
stay on the shelves of the WalMart of the world; they have to keep Walmart happy and not drastically cut Walmart's sales by offering it significantly cheaper online... because lets face it, if it's that much cheaper to not have to spend time/money/gas to goto the store to buy it, you'll definably get it online.
I may be considered biased though, in the interest of full discloser, I am in the credits of Ostfront, and I work on the Mare Nostrum mod which is distributed on Steam and that's possible by TWI.. that aside, I'm also very objective about alot of Valves stuff, but you'll have to take my word on it.
Overall my opinion is pretty well shared with what Ramm stated in the article (and make sure you read the whole opinion). Look at all the indie titles on Steam, and iirc, alot of the Big Names (EA, etc..) didn't happen on Steam until much later... lets face it Digital Distro drastically lowers the bar to entry for an indie game developer. And just because you make your game available online, doesn't mean people will see it.. Having something like Steam means the 60k people still playing the original Counter Striker might actually see that you have an awesome title available.. even if it's for the 1second it takes them to close the window :]
As for the comments left by Alan Wilson, they start at comment #8 on the articles page:
http://www.gamasutra.com/php-bin/news_index.php?story=25595