IT's not that simple. ...if the commission goes away the market will force the price down and the starving artists will get the same amount of money they were getting. After all the term "starving artists" wasn't coined after the iPhone gained market dominance.
Actually it is that simple. If the "starving artist" is selling his or her own creation directly, they can "control" the price for their offering. It won't get pressured down by many competitors selling their app if they are their own seller of their app. The only competition they could endure- which would be the same in the "as is" model- is other "artists" creating a very similar app and buyers opting for the other app instead.
So, app creator feels competitive pressure to be sure their app is the most desirable one among competitors. That's good for us app consumers.
But as controller of their app, they can charge whatever they want for their app, including- if they wished-
MORE than it was previously offered in the App Store. Get too greedy and competitor "artists" will see an opportunity to offer similar functionality for less... so that threat of competition somewhat polices the "too greedy" scenario. Again, this is good for us consumers too.
However, no need to cut their own throat to "< 30% off the top" if they are in control of their own pricing. But they could opt for- say- keeping a chunk of what was going to Apple while still passing through a better price to consumers. Again, this would good for us consumers too... while greatly benefiting the "artist" as well.
The only scenario where we consumers lose in such an arrangement is the "get very greedy" for a highly desired app scenario. Again, competition seeing high demand but too-high pricing will clone the desired functionality and offer competitive pricing. So our short-term loss becomes a long-term gain.
The only scenario where the "artist" loses is in opportunity loss by perhaps pulling their app from the App Store and finding that even with the 30% cut, they made more money by being there than going their own way. If I'm this developer, I don't pull my app from the App Store to maintain those sales... but I probably do sell direct too for a lower price. Customers who buy direct from me will be more profitable sales while getting a lower price. Customers who will only buy my app from the App Store can still buy my app from the App Store.