Cold Calling

[spy587]

Long time lurker and relative beginer to poker here. Could someone explain to me the reason that cold calling is such a heinous act. If you look across the forum I often see people describing their leaks as cold calling too much, and I agree that it is bad to have a lack of aggression when you should actually be reraising instead of calling, but it often seems to me with fairly good hands in many cases it would just be best to call. Help on this would be greatly appreciated.