All I ever see is people begging for witness votes, but what do they actually do?

Maintain security and reliability of the platform. Produce blocks. Sometimes they do some more with their user / investor hat on.

I want to either have the SBD either permanently pegged to the USD, or removed, that we would have the witnesses vote on it, and take some action afterwards.

First, please read the Steem Whitepaper.

Any time SBD is consistently trading above $1.00 USD interest payments must be stopped.
^{- The Steem Whitepaper}

And that's exactly how it was.

In a market where 0% interest on debt still demands a premium, it is safe to say the market is willing to extend more credit than the debt the community is willing to take on. If this happens and SBD will be valued at more than $1.00 and there is little the community can do without charging negative interest rates.
^{- The Steem Whitepaper}

Getting rid of SBD was considered, among other solutions, the consensus is that SBD stays.

Instead, they are absolutely pointless, and just reap the rewards of earning more Steem than the rest of us, without actually doing shit.

That's the DPoS. Witnesses are the servants of the platform thus platform stakeholders. Adjust your votes. You are free to become one. Or just change the playground.

Am I the only one who feels this way, or are you guys just as confused as to what a Steemit witness actually does for the overall community as well?

What if I tell you that there are no such thing as "Steemit witnesses"? ;-)
The platform is Steem, so those are Steem witnesses. :-)