I expect if you're reading this you'll know about Melan's recent post, "Against Ultra-Minimalism". This post is an orthogonal response to that.
My basic idea of a good game book (whether a good rule book, good module, good bestiary, whatever) is that it should be well-designed - which typically means efficiently designed - and interesting to read. Those are the platonic ideals. While the design should therefore be "minimalist" in a functional sense - it should be minimally complex, i.e. only as complex as it needs to be - the approach to content is subject to a totally different set of considerations. Give me good, interesting, exciting, readable, imaginative, dare I say even poetic, prose. I don't want to read a rule book written like a car manual. I want to read a rule book written by Proust, Ellroy or Vance. I don't mind how different the style is, but give me style. Give me voice. Give me something good that I actually enjoy reading for its own sake.
By the same token, I don't want to read a book full of "This is a bronze-age village exporting pitch next to a bunch of Vikings and a colony of 15 ents." I want a rule book full of real ideas to inspire and entice - ideas that mean something - and which I wouldn't have thought of myself. I can't get enough of those.
So I don't actually mind how long a rule book is, if it's genuinely well-written and imaginative. I tend to prefer shorter books because most RPG writers are completely dreadful at writing and pretty unimaginative. But if you can write, and have good ideas, why go minimalist? Give me more of it. Be as maximalist as you like. Misty Isles of the Eld could have been twice as long and I'd have still loved it. Ditto Maze of the Blue Medusa. I want books, like those, that are brimming with invention, not limited by the false modesty of minimalism. "Less is more" as a principle is over-rated; you can over-egg these things, but nobody ever talks about the dangers of under-egging, which in my view are all the more pernicious because that sort of approach tends to take on the character of an orthodoxy which cannot be questioned.