You are correct that at JET there is no tech installed to absorb the neutrons, nor will there ever be in JET, since (as pointed out above) it is a _research_ device.
Current fusion devices are not nor were they ever designed to generate electricity for a grid.
This is why we build ITER, and DEMO thereafter. Generating 'usable fusion power' is limited to building reactor scale experiments, which to date, has not been done (ITER will be the first).
59 megajoules of sustained energy ^over the course of a few seconds^.
Ideally this energy output would be sustained for days within ITER.
JET is not designed to do this, as it has a copper magnet system, which means if you try to sustain such a plasma (confined with around 5 T magnet and around 2 MA plasma current) for longer than a few seconds, you would melt the magnet.
Edit: ITER would operate at 5-10 T, and around 15-20 MA plasma current.
I wouldn't say the (recent) past was grim, but rather that the technology to build an _affordable_ commercial device had not yet been developed yet. We designed and built ITER at such a large size and cost (€20 billion) since high temperature superconducting magnets were not yet available.
In the meantime, all of the experimental devices (JET, AUG, EAST, DIII-D, etc.,) have been gathering evidence on how to operate ITER when it is turned on, and not necessarily focused on achieving breakeven.
The hefty price tag seems smaller when considering the development and design of ITER began during the cold war.
The literal size is definitely big even without context, which is why it has the nickname: gigantomak :D.