I'm currently doing an analysis of the system, might make a post out of it next week.
One of the main issues really is that many many stakeholders are not voting at all. While many big stakeholders have a huge impact on the election of the top 20, the bigger problem is the possibility of a single stakeholder (steemit inc for example) to overthrow the entire system all at once.

I'm analyzing if removing the voting limit would help, but if people don't vote more it doesn't change anything at all (coverage doesn't seem to improve a lot).

Reducing the system to 10 votes, would allow Steemit to elect 10-15 top witnesses (which is better than 30 but still not satisfying).