To be blunt, some of the builds look a bit gay to me.
... and there's just something about that Miyata that makes it look totally right.
Is the irony here intentional? The gold accented Miyata would surely be Liberace's bike of choice.
There's no irony. The Miyata isn't my type of bike and may not satisfy my definition of a mountain bike, but it is well designed and I believe it is presented here precisely as the designer intended. Some of the builds in my view present the bikes as slightly camped-up versions which give an overall impression that seems quite different from what the designer would have had in mind, and may even get in the way of the intended function.
To me, a mountain bike should look as though it's meant to be on a mountain. Once you have a build that looks as though it isn't intended to leave the owner's garden, or as if he wouldn't want to risk getting mud and shit on it, it ceases to be a mountain bike. That isn't to decry the excellent work that people have done, but everybody has their own view and that is mine.
And although I'm no expert in Liberace, I doubt whether he would like the Miyata the best. True it is ornate and I see why you say that, but I think it has substance. To the best of my limited knowledge, Liberace was all about ostentation and the key to ostentation is a lack of substance.