I know that your are rewarded with bages for x amount of helpful flags for closing duplicate questions or off topic etc. However why dont you get any rewards like +1 for flags that others agree with when others get rewarded for answering the question without flagging by simply looking at the duplicate post. Would it not be beneficial to add rewards like +1 for agreed flags?
Ambiguous original post is ambiguous - this section makes the assumption that "+1" means rep.
Just like voting in Meta doesn't get you rep, you shouldn't be given rewards for flagging things for moderator attention, or marking things as spam, etc. on the main site - if flags got people reputation, it'd be an incentive to make flags necessary which opens a whole can of worms.
You aren't required to do flagging, just like you aren't required to participate in Meta, or vote on questions and answers, or comment on things, or to close things with close reasons if you have that rep, or to cast deletion votes. (You don't get any rep for any of these things!) You do those things because you wish to do so.
You shouldn't be given a tangible reward because you wish to contribute to making sure the site is cleaned up. Sure, it helps to clean up the site, but consider spam waves - those of us who flag all the spam as spam would be gaining massive amounts of reputation, and even moreso there will be people who INTENTIONALLY spam just to gain rep. The reward for doing this is the satisfaction that you're helping the site.
Adding rep gain to flagging things with "good" flags that are marked as "helpful" will only be an incentive to spam to gain rep, and such. Lets not open that possibilitly up. (To implement here may mean global implementation, which opens the entire Stack Exchange network to that evil, so...)
Ambiguous original post is ambiguous - this section makes the assumption that "+1" means an additional flag in the amount that can be used that day.
Why would this benefit the site if everyone got an additional flag for every successful flag? If you want to moderate the site, gain reputation, do flagging and identification of things that're bad normally, don't try and get "more" power just from doing something good for the site. Same as my other assumption, with "No Rewards!", that applies here - you shouldn't have to be rewarded just for helping to try and clean up the site. Besides, usually when flags are handled, they take TIME to be handled, you won't see the reward because if you go to bed or something and the reset happens, you lose that 'returned' flag power.