I speculate that if there was a way for them to access the funds, even with a penalty if the emergency was to happen, they would probably power up and be more comfortable with the idea of long term, simply because there is a choice.

I am into this situation 100%. If there was a possibility to instant power down some amount of Steem I would have invested my own money into SP and not only what I earned with Steemit and that's the words of a plankton...
To answer your question regarding if that would help the blockchain I would say definitely yes. People would probably buy more Steem and power up knowing that they could access it at any time even at some costs. It wouldn't bother me to pay a 10% on an instant power down if there would be such option.
Meno you have my vote and resteem for opening this topic. It is something I have been thinking about many times before.