A mature discipline means highly experienced experts. And the thing about experts: they can tell you what can already be done, and tend to reject anything different than what can already be done.
It's a well-known caveat. Experts would rather focus on the flaws of the alternatives in order to "disprove" their viability, rather than try & find solutions for said flaws.
This solar panel technology may not have all the benefits of traditional roads, but it has benefits which traditional roads don't. It's not possible to really know which set of pros/cons is better for us today, before the technology is tested and iterated upon, to weed out the inevitable issues that will pop up.
Any new technology in the history of humanity has failed the "thought exercise" experiments of those deemed experts at the time. Cars, computers, airplanes, heck, even computer mice were called "impossible" at some point.