>User options are good.
I disagree in some levels (human-computer interaction research supports this, more options imply more probability of human error), but let's focus on voting system.
It does changes the behavior of the uses even if it's an option. If the vote become on default, then the point will be: will it be enabled (visible) or disabled by default?
Even if it's disable by default and as user choice to view it, a vote can became an reward (positive reinforcement, in Skinner's Behaviorism) and will facilitate creation of an authority figure.
To understand, take a look on Aristotle's division about arguments:
- Pathos: emotions
- Logos: reasoning
- Ethos: authority
On good discussions (where the truth is the only important matter), it's ideal to not have pathos and ethos, although we are humans and they will appear in forms of cognitive biases at some level. [the exception about pathos is where humor is allowed, or when rhetoric devices such as irony is used to express a thought].
The removal of "Ethos" is the fundamental point in imageboards. Without ethos, an identity, we are free to talk what we want, because we don't have a social pressure.
You see? That's the basis of our community. If you change that, you lose.
The votes create Ethos. Ethos creates identity. Identity creates social pressure. Social pressure is an inhibitory factor.
Therefore, you should not allow it.
Some introdutory material:
I don't want to sound pretentious, by the way. It's just my view on this. But, I'm pretty sure of what I'm saying, if this feature starts to be implemented on imageboards, they will be dead in some months.