I don't think it's disappointment so much as confusion (presumably due to word count?)
Your explanation of the effective firepower approach makes perfect sense, as does why you should use half the "canon number of emitters." The confusion comes about because that suggestion and those explanations are not present in the NG, which just leaves the uninformed making wild guesses as to what the firepower should be.
A classic example is the b'rel-class scout - on screen we clearly see two disruptors and a torpedo tube every time it's in combat. The natural tendency is to build two mounts into the CODA version, but by this rule of thumb it should only have one (which makes sense, as they both fire forward) - which just looks... wrong!
Add to this the fact that we have no idea, for example, how powerful a b'rel's disruptor is in comparison to a Type XI phaser, and I hope it becomes a little clearer as to the source of the confusion!
If I might make one teeny after the fact (but hopefully constructive) comment, it might have been better to drop the offence value and space costs of the individual emitters by half, and double the number on the example ships. This would have had no impact on the gameplay, and moved the whole debate out of the public arena.
Just my thoughts, and no reflection on the system, which I still say is one of the best I have seen in a non-dedicated book.
Jon
"There are worlds out there where the sky is burning, where the sea is asleep and the rivers dream; people made of smoke and cities made of song.
Somewhere there's danger, somewhere there's injustice, and somewhere else the tea is getting cold. Come on, Ace, we've got work to do."
THE DOCTOR, "Survival" (Doctor Who)