(jumping in ...)
The point here is not "style over substance," but that style is substance.
Certainly, one may make a useful point in a clumsy way, but the converse is not also true: It is immensely difficult to write well without also saying something worthwhile. And the primary business of any critic is not to explain, or to define, or even (and here we break from our predecessors) to "create a taste," but to keep the conversation interesting. He will be hard-pressed to accomplish this latter task without having incidentally advanced the aforementioned goals in the process.
Or, more simply: Life is far, far, far too short to read much dry criticism.
Which is well and good when we are talking in the abstract, but how, exactly, do we define "good style"? Well,
Criticism of a work of art will sometimes of necessity be imprecise, but we look for precision in the writing itself. We posit here that no matter how complex the idea that you are trying to explain, there is rarely an excuse for wasting our time by being obtuse.
(Which, admittedly can get in the way of (1) half the time, but nobody's saying this is supposed to be easy). It's worth restating this point: There's lots to read out there. Meaning that you have a massive amount of competition (in the general sense of "other potential reading material") for that Ecocritical analysis of Book III of The Faerie Queene you're working on—so don't be upset when readers put down your treatise in favor of yesterday's New York Post on the grounds that the latter is better written and more fun to read. They're probably right, and you should be ashamed of yourself.
Seriously. It should sting.