Read your whole post Rhodescrhoma, very interesting.
As to all the hating-on stuff contributing to ENT's demise, I doubt any exec's making decisions had any idea of it. They are looking at the raw data, viewers, cost, advertisers.
A lot of the haters were actively hating VOY before ENT came out. A lot of haters are just Trek luddites IMHO. They had their peak Trek-love experience with one of the earlier series, probably when they were younger and at the age one bonds with an alternate universe, when it was exciting and cool. Then they got older and they were no longer going to feel that way about anything.. but they take it out on the series that are released post their peak. I was on one mailing list where I watched the VOY bashing move into ENT bashing, horrible stuff.
I agree
almost 100% with your post, however, in this case I believe (and, of course, it's just supposition) that execs were looking beyond just raw ratings and advertising data with this particular product. ST was / is so huge for Paramount, and, according to media reports I'd read in the past, the studio had pretty much decided that ENT was not what they wanted carrying the ST torch by the middle of S2. Sure, they let it run on (and Paramount made sure thru their "subsidy" to UPN that they'd have enough episodes for viable syndication) but the franchise was so irreparably splintered after VOY and then the beginning of major ENT bashing, that I don't think that escaped the boardroom from the very beginning (in the form of, we'd better reunite our core viewership after what went down with VOY, or this mission is going to fail, and we're going to get out from underneath it sooner than later. Now - in the same breath - I'm not sure if anyone at UPN was ever thinking at all :-) but, if they were, it was surely along these same lines,)
The hating on VOY, transferred soon enough onto ENT, got so dominant even beyond the ST fan base to non-ST focused media, it became an object at least in the back of everyone's mind at the time. No one was allowed to like ENT or support it without fear of "reprisal

" from their given ST community - some of this, obviously, and unfortunately, still exists today, though I don't care and am happy we got our 4 seasons to enjoy. Just looking at archived articles about episodes of ENT from back during S2 and seeing the comments left by viewers - wow - a nasty bunch.
I was not active on the forums/boards at the time of VOY's ending, nor at the beginning of ENT, but I did (as I alluded to above) take a trip back thru memory lane before responding to your post (so I could see exactly, first hand, what you were referring to) and it was pretty nasty, and sad. St fans gave ENT such a short time to find it's footing and then it was worse trashing than VOY.
Overall Point: You hit the nail on the head in your last paragraph. I couldn't have phrased that better, though I wish it simply wasn't the case.
Again - so sad for a fine cast to have been slaughtered by it's own supposed fan base, missteps in execution and writing aside. (plus, I still stand-by my opinion that the first season of TNG was just horrible, but it was allowed to slide because people simply wanted more ST. That show took as long as ENT did (maybe longer) to find it's true niche and footing... but, as you said, by the time ENT (and VOY, for that matter) came around, people had already had their love-affair and had moved on.)