Measuring a stake pool's efficiency

In order to determine a pool’s performance the design specs propose to use the “perceived performance” which is basically defined by amount of produced blocks divided by excpected blocks for a given epoch. The performance faktor is multiplied with the pool rewards and thus has a direct influence on delegator rewards.

For a pool to reach 100% performace it only needs to produce blocks, the density of the block doesn’t matter. Of course the incentive for the pool operator to put in as many transactions as possible in a block is that she will benefit from the increased reward pool for the epoch since all transaction fees are accumulated there. But if the pool’s hardware is not powerful enough, especially once Cardano has smart contracts, the number of transactions put into a block might be less than optimal.

The problem is that the pool will not be punished by receiveing less rewards and so the delegators also won’t have any incentive to abandon the pool, as long as it performs 100%.

Is this an actual problem or am I missing something here?