They were discontinued because the mounting position puts them in line for all the worst gunch the road can throw at a bike. Even hard-working long-suffering bottom bracket bearings are not so directly in the line of fire. Building one with fully shielded bearings, as opposed to the little dust covers on most cartridge bearings, would be cost prohibitive and heavy. Half the potential market for these is also using fenders. Look at the photo above and imagine what a fender would do.

Current battery lights are really good.