I've thought about it some more. Taking advantage of a tax loophole is like finding a wallet on the ground and not returning it to the owner even though the owner's contact information is in the wallet. Taking a tax deduction is like returning the wallet to the owner and accepting a small reward for your good deed.
What you're saying is that anyone who criticizes someone for keeping the wallet should be criticized for being willing to accept the reward.
ETA: Another analogy would be the following. You're checking out at the store and notice that a register is unattended. So you take some of the store's money and walk out. Is that really the same as using a coupon offered by the store for a discount? A loophole is by definition unintentional. Taking advantage of it is no better than stealing.