I think one of the things that has evoked the response you've encountered is the wording you've used. You make a fairly "matter of fact" statement about post-processing techniques being "overused". I think that comes off as very argumentative to many readers, and since its your first sentence, I think thats set off a lot of readers the moment they first read your question. First impressions, and all that jazz. I'm sure this wasn't your specific intent, and I make the same mistake all the time...I state things pretty "matter of factly" by nature most of the time, and it ticks people off in most areas of life. ;P
From a content perspective...it being art rather than technical, shouldn't be a problem at all. I think most of the people on this particular SE site fully understand that we tend to be a rather unique member of the StackExchange community. We have a lot of subjective areas, and we can't (and don't want to) cut out those areas and solely focus on the technical side of things. We have covered the technical side of things more thoroughly largely due to the fact that a lot of the initial membership have technical backgrounds and came from the more technical SE sites (like myself, I came from StackOverflow.)
I think many of us very much want to see a more artistic, rather than technical, focus on this site. Photography, while it is built on technology and has some very technical aspects, is first and foremost a form of artistic expression. I think questions like yours are an excellent addition to the content here.
That said, I do think your question needs to be reworded. It definitely comes off rather bluntly as "this is fact", when in fact the use of post processing techniques, whether overdone or not, is one of the most critical factors in artistic expression in photography today. Its not simply that using a heavy vignette is bad in and of itself...its whether a heavy vignette is used artistically, or in bad taste, that really matters. That sounds really subjective, but I think there is...for lack of a better term, an artistic science to it that can help viewers discern the difference between artfully tasteful, and in bad taste. You might want to factor that into the way you approach the question you are trying to ask.