The other issue is telling your customers "its costs to much to do that" you never ever tell your customer that it makes the company look bad and it made him look incompetent just very poor customer relations.
An extremely interesting and well argued no though....
I agree with your point the more developed dev posts even if the summary is "no", "hell no" or "you're joking, right?" tend to produce better responses than the usual EA PR approved fluff that seems to be the hallmark of the limited communication in this game.
Probably the best example of how to do it I have found on this forum is the dev post in the species request poll talking about what is practical given the engine and given that constraint what is practical for story and lore. Admittedly not everyone responded well to the post which is unfortunate but the response was overwhelmingly positive that the dev had taken time to respond and even more explain their stance - even though the answer was mostly "this won't work because". The "because" is really important in these kind of posts.