Because cash societies - especially between nations that use fiat currency - still rely on resource management and control as the backbone of capital generation. Not only would the world need to be cashless, but the would have to be an elimination of even the notion of a superpower, and the world nations must be united working together as citizens of the planet. No nation could solely own warp technology without being targeted for erasure, or unless every other nation could develop the technology too. This is one reason why nuclear arms races happened, and why "rogue" nations are trying to work the technology.
Free energy would kill the entire energy market (and capitalism altogether,) and before we get to warp drives, we would have to introduce free energy on a consumer level (it is already a reality, Tesla has crude working models.) There would have to be a justification (progression, LTE) as to how such a technology came to be - for the sake of the "thinking layperson."
But free energy would also allow for everyone's needs to be met, which would (ideally) catapult the world into the space age (as we will more likely work together for the common good of the world since we don't have to compete with each other for resources.) Basically, the predictive psychology is that we would need to be in a form of worldly socialism in order to be in the space age. This same philosophy was shown in most Sci if movies and shows.
It is also the philosophy of the "illuminaughty," but the means to which they reach the goal is the troubling part. But, you can see why they believe their logic is undeniable: it will propel the world into "unity, safety, and peace" where we can explore, learn and grow unbound, as all of our energy needs would be met. No more war, no more system, no more horrors...