I am guilty of only commenting on points that interest me as well. 
 
	 
 
	From my perspective its because commenting on every single point someone may make in a long post is exhausting, I have no intention of debating every aspect of every topic, and others will talk about it if the point that didn't interest me at the time resonates.  Maybe then Ill have an interest, maybe I won't.
 
	 
 
	As to bad design?  Lol, this whole game swims in bad design decisions.  A lot of them are worse than Rage.