Mac App Store is still a nice idea even if the offerings are slim at this point. Problem is, unlike iOS devices, you don't need it to buy software for your computer.
Apple needs to come up with some compelling reason for software publishers to want to sell software through the Mac App store.
The compelling reason is going to be 'volume'.
Independent software sellers now might get 1000 hits a week and sell 10-20 copies to wayward internet travellers who manage to stumble onto their site, navigate the various scary looking payment systems, etc.
But with App Store, customers go there looking to buy. They are accustomed with the format, the distribution, the payment. It's all seamless and familiar to them, so they buy. That independent seller might move 100 or 500 copies due to the massive exposure and customer convenience. Of course the volumes can and will have a dramatic effect on price points. People who would never shell out hundreds for Aperture are gobbling it up at the $80 price point. And Angry Birds would be bargain bin fodder at Staples if they tried selling it for $39.99 or $19.99. But at $3-4 impulse download, they'll sell it a million times or more.
Would I give Apple 30% of my sale if it meant my sales went up by 90,000% ?
Sure. I might resent their greedy cut, but the giant cheques rolling in would take some of the sting away.