> The tradeoff [...] could be equity (which could confer voting or board rights to you to monitor certain things about the company financial health)
If you have that, then you have significantly elevated access to the information you were talking about, and you're already landing on the side of protecting the company. The issues you raised don't really apply here.
> [...] vacation time, conference attendance, foosball table access, etc.
If you value those on par with your salary, then I have a job for you! ;)
> I don't see any fundamental reason why these couldn't be negotiated as part of an employment agreement.
You're right, there is no reason. You can and should negotiate these things. Negotiate away!
Just recognize that you may have multiple conflicting interests within yourself. If you want access to confidential company information about others, you're implicitly requesting that they have access to confidential information about you. Most of us wouldn't mind knowing everyone else's salary, and most of us don't want others to know ours. Most of us would love access to the personnel reviews of our co-workers, and most of us would be mortified to let them read ours.