Besides speed, there are other reasons to move toward fiber optics. One is that once the cost of manufacturing fiber optic lines drops, it should become more affordable than copper-based wires. Glass is relatively cheap to make -- it's essentially sand.
You'll even be able to daisy chain devices together with Light Peak cables. In one demonstration, Intel connected a computer to an external hard drive using Light Peak cables. Then, Intel ran a second Light Peak cable from the external hard drive to a high-definition display. The computer recognized both devices and could send video to the display while pulling data from the external hard drive. This demonstration showed that Light Peak wasn't just fast, it proved it could carry data using two different protocols over the same length of cable. It also showed that you don't have to plug each peripheral directly into the computer -- you can use peripherals as a sort of hub.
Another advantage is that fiber optics can carry a signal without a drop in quality over a longer distance. The maximum length for a USB cable is around 5 meters (16.4 feet). But a fiber optic line can be as long as 100 meters (328.1 feet) without a drop in quality. And the fibers in Light Peak are only 125 microns in diameter -- that's about the diameter of a human hair. For applications that require long, lightweight cables, fiber optics win out.
Copper-based wires have another problem -- interference. Copper is vulnerable to radiofrequency (RF) interference, which can result in quality problems. But fiber optics use light, which isn't affected by RF leakage or radiation.
Has Intel run into problems developing Light Peak? It's hard to get information out of the company but one indication that development hasn't been as smooth as it could be is that the first generation of Light Peak technology will use copper rather than fiber optics to carry data. According to Intel, this is because engineers discovered ways to push copper's performance beyond what they thought was possible. But why use copper at all if fiber optics are the future?
It could be that Intel is still perfecting the fiber-optic technology and plans to use the copper wire as a stopgap measure. Early press releases on Light Peak suggested the technology would begin to appear in products beginning in 2010. Intel pushed that timeline back to 2011. While there's no confirmation that engineers have hit obstacles while working on fiber-optic solutions, there's a chance that manufacturing challenges or performance issues have slowed down development.