I would prefer a balance. Planets bursting with varieties of alien life is certainly to be expected, but I really don't want every single world we visit to be something like the Hinterlands except with sci-fi textures swapped in.
The barren emptiness of a small planetoid, its atmosphere blasted away by the looming blue supergiant, can be just as interesting (if not moreso) than a valley filled with frolicking willow bills or grugglmoths. ME 1's problem was the overuse of procedurally generated maps with no character. The atmosphere (no pun intended) of the barren planets was there, its just that there was nothing really worthwhile to do on those planetary bodies.
I wouldn't say the Hinterlands were populated at all. I suppose if you count plants, but I took fauna to be more of a reference to animals (in the colloquial sense). So I was thinking of worlds that did not necessarily have what we would recognise as plant life, but did have life (even if was alien and in environments wholly inhospitable to ME sapients).
My main objection to the rock planets is that they're unbelievably boring. There's absolutely nothing interesting about a hunk of rock. There are ways to make planets devoid of life at least visiually interesting if nothing else, though that usually requires some form of life to add in colour.
The problem in ME1 was that the barren worlds had NO character. They were all interchangeable hunks of rock, and the fact some had more interesting skies didn't make them any less boring or generic (as against each other). ME1 took a totally uninteresting concept and copied and pasted it.