why not simply low the reward to 10 doges block or something similar?
$0.00126 per block? We need to motivate the miners to care enough to bother both with storing the blockchain and actually applying updates (this is a particular point right now as we've just released the BIP 66 security fixes which introduce an updated block version). That would work out at... ~$662 per year split between all of the miners.
For comparison, Bitcoin currently pays $8,000 per block (or thereabouts), even adjusting for the block time, that's $800/minute. We currently pay out $1.26/minute. If the two coins had comparable market caps, we'd still be paying out about half what Bitcoin does right now.