[panabee]

exactly, so not sure whether the original assertion (i.e., most characters lack semantic meaning) is correct, but it's an interesting thought to consider.

someone could prove/disprove this by analyzing the 3000 most common chars and indicating what percentage contain a semantic component (even if obfuscated).

do you know if wikipedia or the parent is correct about 正 as the radical for foot?

[nonabelion]

Wikipedia is correct. Radicals do carry a lot of semantic meanings. I think the most apparent examples are the names for chemical elements. For example, the radical 气 means gas. Hellium in Chinese is 氦，hydrogen is 氢. So look at the character you immediately know the natural state of the element. Moreover, even if you don't know a character, if you see it has the radical, you can guess what that is related.