Your thinking inside the box still.
No need to be an ass. The box is here, we like it, it needs to be how it is. There are many boxes like it, this one is ours, like it or leave it.
Yes I Haven't reviewed the source code but I will soon. I'm new to programming and bitcoin is not the first project that has made me want to learn how to code.
BOINC already has a credit system in place. It shouldn't be too hard to apply some built in limiting scheme to make the credits level off over time.
The same concept applies, instead of a block chain you have a "solution chain". Yes I know each solution would have to be in some kind of hash form to fit in a merkle tree. Maybe not, the solution chain would just be large and would have to be trimmed frequently compared to the merkle tree configuration of bitcoin.
The idea behind bitcoin is to use as little resources as possible to store and transfer actual useful information (transaction data) (because it costs to store and transmit data). However for securing the network, each progressive transactions block must be harder to create than the previous ones, such that increasing the technological computing power, it is impossible to retrace your own blockchain and replace the one in existence just because each block has the same complexity. I have used BOINC exactly twice and I like the concept.
You have to decide what is useful: processing data that may or may not provide new valuable information to the world, or produce guaranteed unique cryptographic tokens that are impossible to fake, rework, deteriorate or replace, for the purpose of economical utility and reduced resources waste.