Panic and OmniGroup were big 10 years ago. The fact that nobody has appeared on the scene, innovated and become a name that you or I can quote is quite telling. Where is the new blood? I personally know many long-time Mac developers who have sold their products to others to maintain, or have quietly slipped away and let sales slide.
The 30% fee is not an industry standard that was debated and researched and rationalized. It's an abitrary number picked out by Apple first and then followed by others in order to maximize income from the work of third-party developers who are forced to pay or quit the platform. It's a de facto standard imposed by the platform gatekeepers. Calling it an "industry standard" sounds like it's an ISO recommendation :-)
There is no reason at all to charge a $99 fee to developers given the vast income generated from the 30% and the overall health of the company. This is nickle'n'diming developers. Some people claim that "Apple Developer" is a cost-center, an independently run business silo that must generate a profit to justify its existence, that it's not a charity... i say no. It contributes to the overall well-being of Apple Inc as a whole, just like human resources and research and development does, it helps contributes to the overall profits of the company, so when we look at the company's overall financial health, in my mind, there is no doubt that developers are being taken for a ride because...
...they have nowhere else to go because their Apple centric skill-set is not transferable to other platforms.