Block rewards were never intended to be a lottery.
Does that automaticly make it a bad idea?
Amongst other reasons, it is an incentive for miners to do the work required to secure the network.
The fees should be incentive enough, if they couldn't serve that purpose Bitcoin will have a problem in the future too
And if the 'random reward' was sent to, what-- random addresses? Everyone would be mining addresses.
They are going to a random address in the last block, and I already explained how one could prevent users from creating dummy transactions to gain an advantage, so 'mining addresses' will be useless.