Ujl, the veda's defense is more relevant than my personal opinion. (but I'll share my thoughts). Before that, please first address my question from the previous posting. Why symbolize some animals with poor animals? If they deemed symbols so necessary, then why not create the image of self during Yagna and do sacrificial rituals? Like, "here I burn my effigy that represent lust." Why goat? And yet, why even kill, just symbolize the cease of a lower attribute? To me, that doesn't teach peace. It is very barbaric. People who call themselves Brahma should know better to symbolize their actions. 

Please shed some lights.