Indeed, if they just slapped it in there like a modular daughter-card and hooked it up the the power supply (blood, etc) but it doesn't actually work for what most people consider eyes to be most useful for, it's a significant datum that radically changes the interpretation. Still cool, but important detail.
I think maybe the reason people will read the headline and expect a fully functional eye is because most people will drastically underestimate what an incredible feat this is. It isn't much of a stretch to say eyes are a part of the brain that's sticking out.
If a headline talked about the first dorsal amblugda transplant (or some non-made-up component of the brain's anatomy), I would not expect it to be functional. I would be very impressed that they managed to "slap it in there like a modular daughter-card and hook it up the the power supply" although it wouldn't occur to me to use a metaphor that makes it sound in any way simple.
