First of all, it is a meaningless statement. It is a bit like saying "we have not yet decided on the value of Bitcoin". Miners may presently exclude transactions which do not have fees associated with them. And users may include fees as they wish. But presently there is no need to do so because the transaction load is trivial compared to what the network can handle with really no additional overhead. When users choose to include transaction fees at this time it is more like saying "thank you random miner for helping to make our network strong, here is a small donation".
the regular client already enforces some transaction fee rules to avoid spam and DOS attacks.
when it is decided by only a few guys that the official client only accepts transaction with a certain transaction fee and there is no "revolt" by users, miners cant do anything about it.