First of all, it's not just Magness. I doubt that Ayana even had her spikes off before Greg Lautenslager turned up on Facebook calling it "the most obvious display of drug use ever." Sonia O'Sullivan said you have to ask questions when a 23 year old probably drugged record is destroyed by such a margin. Steve Hoag's first comment on Facebook was about it being a tremendous performance. His second comment was "I hope it's clean."
I think Hoag's comment is probably the best one to make this point. Even someone who is really impressed with it can't simply accept the result at face value. You compared Magness to the Boy Who Cried Wolf. Well, in that fable there was ever only one wolf. Now there are dozens, maybe hundreds of wolves and rather than wait patiently for irrefutable evidence of one, The Boy would serve his compatriots better by crying anytime he thought there might be one because a more drastic sort of intervention is needed.
Some of us asked questions about whether Kenyans were doping or not and had Canova assuring us that they didn't and even if they did he said it did them no good because they were too fit for EPO to help. I was having dinner with Arthur Lydiard, for whom I have unbounded respect, when he told me that he thought the East Germans were clean and we see how that turned out.
Nick Willis said somewhere recently that he thinks the sport is cleaner now than it's ever been since he's been in it, so yes, I agree with you that people have worked to improve it and have had some success. But Willis is one of the people who, like Magness, has made comments about how widespread drug cheating is and has been criticized soundly here for doing it. The people running the sport have no credibility anymore and maybe, maybe, seeing the public reaction to stellar performances is disbelief will shake things up a bit. So I think all of the people questioning this time are doing the sport a service even if they're wrong in this case.