The author is absolutely correct, look at the IDS evasion techniques provided by MetaSploit - its amazing and bypasses most signature based IDS system.

However, many times I have seen that hackers just use the public version of exploit and dont make any changes to the code.

For example, how many javascript exploits now just use the keyword sprayslide ?

32 at milw0rm : Google Query for Sprayslide on MilW0rm