The kicker is pretty simple.  They "guestimate" how much they will need to do whatever they are going to do.  

If they take more money than they actually needed away from the taxpayers, they have to give it back. 

If it weren't for the kicker in the Oregon Constitution and the 2% fudge factor, they could "guesstimate" 50% more than they actually need, take it  away from the taxpayers, say "Oops!  and then keep it for new spending,

The only thing a politician has to give is someone else's money (the taxpayers) to the people who will re-elect that particular politician.  

New spending!  On favorite projects and newly-discovered needs!  Sing paeans of joy!

Without the kicker, we would have to rely on the honesty, integrity, self-discipline and fiscal responsibility of the politicians in Salem.....

Right!  

And pigs will fly!  

And unicorns will frolic under rainbows which all will have pots of gold at each end surrounded by magic money trees!