The restrictions are along the "meta" parts (voting to indicate the quality of an answer), I think it is entirely sensible to restrict these actions to users who have built up a currency of trust within the SO community.
That being said, I think you are onto to something around the user experience. Perhaps an option shouldn't be shown to someone if they cannot perform it.
That would be really annoying, because you wouldn't know that these options exist, until you could use them (i.e. you're possibly confused and you don't know what the reward for collecting reputation is.)
Better grey out the things you aren't allowed to do yet, so you can see them and see that you're not there yet - preferably with an explanation of when you will be.
I forgot what the term for this is, but I think it's very often a good way to do it. Stable interface? Something like that.