An excellent breakdown!

It's important to note that the fee schedule rework was implemented when BTS were approx .75 USD each. The market has fallen a long way since- and this is a drawback to a flat rate scheme.
Your 4x proposal would put it just about on the same track.
However- I believe this to be short sighted if we expect the core asset value to rise again.

While it's necessary to adjust occasionally, we don't want to overdo it- as users prefer as much stability as possible.
Perhaps we could consider setting a periodic fee review and correction- adjusting the schedule to reflect the moving average value of the core token within that time frame.
It would additionally give the opportunity to weigh the effects of recent changes after the adjustments have been implemented.

I'm not exactly sure about the consequences of reducing witness pay.
Is there a reason a worker proposal was required to additionally subsidize infrastructure? Why not consider eliminating that expense instead?

It seems like campaigning to meet a break even state is optimal, however this often turns into a constant battle that could potentially deter people from providing infrastructure, contributing to the network or voting in new workers. (While long standing, potentially less important ones soak up the bulk of potential and never get voted out)
It's a tough thing to balance and needs consistent, in depth oversight.

Alternatively, worker turnover rate could be increased in an effort to reduce overhead, promote competition and consistently strive to fill a surplus instead of the other way around.
Supplemented by a clear vision and episodic improvement tasks- with clear deadlines, it could greatly encourage growth and contribution.

Then again- That would require more management and oversight to meet the efficiency needs, and fundamental decentralization always chooses to do the opposite, (however potentially offset by the nature of greater turnover rate decentralizing workers...) soooo

Thanks for the fun thought exercise- xD

Best of luck to you!