Why should we simplify and downscale? 
So I think we have to admit that the eco-modernists could conceivably be right in regard to the possibility that what I call hyper-modernism could be done in a green (ecologically benign or even regenerative) way; that we can and should “go forward” toward fuller (but saner) development characterized by intensification/consolidation of human activities.
But, like most modernists, they’re missing something. Scale.
There is often reference to the “frog in the pot of boiling water.” It’s not actually true, but there’s an image of a frog failing to react to an increase of water temperature because the increase is so incremental; an image (untrue) that the frog kind of gets dozey, never reacts to jump out, and gets boiled to death in the end. The image is applied to how the technosphere and the associated urban labyrinth grew up around us and enclosed us over time . . . such that we incrementally lost our grounding and gradually forgot what that grounding was all about.
It was a revelation when E. F. Schumacher reminded us in his book Small Is Beautiful in 1973.
(Thoreau had sensed it. Hardly anyone read Thoreau during his lifetime. When his writings were re-discovered during the twentieth century the focus was mostly on the naturism and anti-statism and civil disobedience. His broader critique of “the direction things are going in” was not fully appreciated.)
With Schumacher the focus was on his concept of “intermediate technology.” Development has resulted in technology that’s too big, too centralized, too complex. It makes people feel dependent: “they” produce our electricity, “they” build and maintain our infrastructure, “they” manufacture our stuff. When will those potholes in the road get filled in? whenever they get around to it.
Schumacher said it’s not, of course, a question of “going back” to simple aboriginal stone-age technics, but there’s an intermediate level that’s comprehensible, affordable, decentralized, human-scaled, people-centered, and environmentally sound — qualities which, overall, foster autonomy.
Likewise, there is an intermediate level of social organization, in-between the nuclear family or clan and the modern institutional Leviathan.
We don’t even remember that we’ve lost it.
Eco-modernism is predicated on urbanism and industrialism. Eco-modernists assert that that paradigm can be made sustainable. But I doubt it can be made comprehensible, egalitarian, decentralized, human-scaled, people-centered; I doubt that it can foster the lifeways-basis that should be a key aspect of the greening of society — communitarian self-reliance.