Also, I know many companies are in the EEA working with Ethereum. Does it benefit the demand for ethers if they are all running on their own blockchain?
Yes, it would be easier. But we have to consider what the private blockchain is for and who is influenced by any good or wrong doing. If it's a corporation, the corporation itself could fail or become target of regulatory or legal sanctions. That's bad for the company, the employees, the shareholders, but not society as a whole. The cool thing about the blockchain technology is that the uses are so widespread. But with anything, if it is designed to fail or if the people using it have intent to make it fail, it will fail.
The question to ask is where is the line to be drawn between what a company or organization can do for their own operations and when the public should have concern over how that company or organization using the technology.
E.g., We all use airplanes for transportation. Drug smugglers also use planes to smuggle drugs. Does that mean that the planes are flawed? Does that mean we should outlaw they use of planes by drug smugglers?
The technology is only as good as the people using it.