I am not sure this is a good question for Q&A so much as an opportunity for discussion, and I am not sure why this is acceptable but questions about a possible connection between crafts and sustainability is not.... With that disclaimer in mind though I want to give a very different answer based largely on the work of anthropologist Joseph Tainter ("The Collapse of Complex Socieites"), and look at the relationship between surplus, complexity, and sustainability. I don't think the relationship is a simple one, and yes there are cases where energy efficiency may make moderate-term sustainability harder to achieve.
I also think it is necessary to take a long view both of the past and the future in addressing this question.
Tainter's Theories on Complexity and Collapse
Joseph Tainter has authored a large survey of societal collapse (meaning, as he puts it, simplification), where the number of societal roles decreases radically, as does the coordination between them. A good example would be the fall of the Western Roman Empire. The survey is The Collapse of Complex Societies and it is well worth reading.
Tainter's thesis is that complex societies collapse by simply becoming unsustainably complex, namely that we add complexity to society to solve problems and that at some point we can't keep that going, so major investments required to maintain a current quality of life usually foretell collapse.
Tainter also directly discusses the impact of energy (in the form of agricultural surplus) in the case of Rome. During the expansion of Rome, the government was largely fueled by pillaging acculumated surpluses from elsewhere (or more properly proxies for that in the form of gold). When this could not be continued, Rome had to move from accumulated past surpluses (representing, as he puts it "past solar energy") to current production (as he puts it "current solar energy"). This move was catastrophic for the Roman Empire and it lead to a spiral of currency devaluation, and eventually the inability to maintain food production up to the level it needed to be.
One of the points that Tainter brings up is that much of the complexity added was actually there to stall the collapse, and that Rome would have fallen much sooner had they not added the complexity that they did. However with complexity comes a large sector of the economy which is largely devoted to regulating the rest. In modern parallels, this would include not only government but also business administration. The more complex these fields become the fewer people are actually producing and eventually the whole thing collapses. The level of detail he goes into is astounding and I recommend both watching what lectures he has on Youtube and reading the book.
We Use Energy To Subsidize Complexity
Prior to the age of fossil fuels, greater social complexity meant that people had to work harder. The difference between a simple society governed by local self-sufficiency generally and a complex one with large amounts of regulation meant that in the second, people had to work much harder to achieve subsistence. Historically of course the best example of this is moving from forraging to agriculture (see The Worst Mistake in the History of the Human Race by Jarrod Diamond). In essence the agricultural revolution meant trading quality of life for larger populations and in order to make that work we see additional complexity arise in societies relating to that.
The same thing applies to the so-called green revolution and the dawn of modern fossil-fuel-based agriculture but with a twist. In the past humans and animals put forth the effort into tilling the soil, planting, harvesting, etc. Now the humans and animals are replaced by machines, and the energy comes not from eating grain but from fossil fuels. Similarly much of the nutrition of the soil comes from fossil fuels instead of decaying organic material, but to build and maintain the machines, associated supply pipelines, etc, many new roles had to arise, and farming came to embody more economic complexity. This of course was only possible because the energy came from fossil fuels, and this was only possible because of a surplus, at the time, of fossil fuel-based energy.
Energy Efficiency being good for Sustainability
One of the largest challenges sustainability-wise that we have is the fact that we are as dependent on fossil fuels as we are both for energy and for materials (coal, fertilizer, plastic, graphene, and much more). Additionally demand for energy is increasing faster than supply and for this reason our individual embodied consumption must decrease at least for now. The larger and more open question of course, is whether being more energy efficient for most of the population just means that their energy consumption can be spread out, where greater energy efficiency of appliances is offset by having more of them (this, itself, may not be a bad thing for reasons below, but it does nullify the effect).
Additionally more energy sources become viable when we become more energy efficient. It may not be sustainable to run cars on sweetgrass ethanol, but it might be if cars were twice as efficient (perhaps fuel-cell hybrids).
Energy Efficiency being bad for Sustainability
There are two significant mechanisms by which increased energy efficiency might lead to unsustainability.
The first is that we have to be honest, that real solutions to problems require large levels of economic investment and consequently if an economy which is based on ever increasing and unsustainable consumption of consumer products begins to falter, it may be much harder to engage in needed projects, such as grid upgrades necessary to guarantee baseline power from wind, or the like. Having more sustainable products doesn't matter of people can't pay for them, and so the simplification of consumption which is needed to achieve sustainability also can thwart that same goal. For example if electricity consumption drops, it is harder to justify investment into wind-based power generation and the grid upgrades necessary to make that happen.00
The second is that if we succeed in freeing up surplus energy we will, as history shows, want to use that energy to solve our problems and therefore the shift will be made from using it in ways which are necessary for human life and towards a regulatory role. This can add to non-productive complexity and make it harder to solve the next challenges down the road. For example, we could see an actual consumption drop in energy lead to an increase in energy consumption in businesses who then use that energy to subsidize complexity of their own operations, or the same for government. The same goes for moving towards higher levels of technology, where greater complexity goes into engineering, manufacturing, and maintenance when compared to relatively simple technologies. Each of these tasks takes energy and consequently, we become far more dependent on energy efficiency and less able to make investments in solving future problems.
I have already pointed to a book written largely on this topic. I am sure many more could be.