I'm not an expert on decoction by any means and I've never setup any formal experiments, but anecdotally I think that people are searching for the wrong things in decoctions. There may or may not be too much of a flavor difference - I've never brewed a side-by-side - but there's definitely a brewing difference. What I mean is my mash runoff is clearer with a decoction, the amount of kettle break I get with a decoction is reduced, and my efficiency is increased. The difference in the appearance of your mash and wort is very evident with a decoction. The change in appearance of a decocted beer in the kettle would lead you to believe that the beer you are producing will be cleaner than in other examples; although, as I've said, I don't have any evidence of this.
Also, it seems logical, a priori, that there would be more of a difference than could be compensated for by just adding some other malt. No one would argue that you could make up for not boiling your wort by adding crystal malts - there are too many processes that occur in the boil, not just carmelization of sugars. Likewise with decoction mashing there is more at work than the formation of melanoidins.
I think the Brewing Network and Jamil have some hand in every forum discussion of decoction mashing I've ever seen. Jamil takes new brewers up the learning curve so quickly that people begin to repeat his opinions as homebrewing fact when they've been presented as Jamil's opinions. Jamil has stated on more than one occasion that he's proven to himself that there isn't enough of a difference between the flavor derived from a single infusion mash with melanoidin malt and the flavor derived from a decoction mash - which is fine. The problem, to me, is that new brewers won't try a decoction and even if they do are consciously or sub-consciously biased against decoctions. I guess my problem is that almost every new brewer has heard Jamil's thoughts on a decoction mash before they've tried one so any "experimental results" they find are likely to be biased.
I think if people were brought up the learning curve by someone like Greg Noonan their opinions would be different because they would have different expectations.
I think the Brewing Network does an amazing job of moving new brewers up the learning curve and introducing new concepts to old brewers it just seems that people often appropriate the opinions of those people whom they respect more than they are willing to search for their own answers. End rant.