I love charts, and technically they're pretty easy to implement. The hard part is picking out 'good' samples. As hwbot receives 300 to 500 submissions a day, the result moderators barely have time whether essential info is correct (correct score, correct cpu/gpu and has validation), so there are quite a lot of scores which have wrongly matched cpu/gpu speeds.
There are multiple ways to solve this: more mods, better tools to detect these faulty scores for mods, or better algorithms for charts which detect bad results. We're working on the latter 2. For example, we just made the 'overclockability' chart better for videocards:
http://www.hwbot.org/quickSearch.do?hardwareId=GPU_337&name=Radeon+9800+Pro+%28498%29
(scroll down a bit). It will take some time before we are confident we can add more charts. Better 1 good chart than 10 poor ones.