The goal is there mostly because humans like goals, but otherwise both space exploration and fusion are about the research happening *in the process.* ITER alone brings hundreds of discoveries in physics, materials, design, logistics etc each year, even though its declared goal is delayed by 5 years (but the current schedule of first plasma in 2025 is feasible).
History of fusion projects (such as ITER) is a good example of the fundamental difference between a scientific and engineering project. Fusion technology is there and we know how to do it for scientific research.
What is not there is sustainable net-added sustainable fusion, where we're not only doing the fusion in the lab but actually have an *economically* viable way of *producing* energy. As opposed to expensive way of consuming it, which most of the science projects do :)
Also as it comes to ITER specifically, it's an unique project with dozens of countries participating, and the objective being research rather than fast delivery of a working prototype. 90% of the delays in the project were specifically due to political & organisational issues rather than engineering or science.
There's a very good book I just found last year "ITER: The Giant Fusion Reactor: Bringing a Sun to Earth" by Michel Claessens, he writes about it in great detail.
This aspect - what is the project objective - is unfortunately notoriously overlooked or confused by journalists and general public in similar projects. For example, in 2010 there was plenty of hype about DESERTEC that was expected to "power the whole EU" out of PV panels in Sahara. It never happened.
Just recently one of the DESERTEC directors told me that the project objectives were actually also kind of mostly research, which would change the perspective - but then, he admitted they too allowed themselves too many far-fetching statements and declarations about the project's objectives. I can only assume this was because hype attracts attention, and attention attracts funding. But then, the "failed" labels sticks to the project forever...
