I think a stronger penalty is in order but what needs to be kept in mind is sometimes due to glitches a person may appear to have dodged when they havent. I've thought that maybe if instead of a 15 min ban on aram a 15 min ban on all lol game play might be more effective. Another solution is a steep increase in the penalty time based on frequency of dodging.
I dont know much about smurfing but that does seem to be something which will undermine any attempt at controlling behavior. If someone can simply logout and log back in under a different account they can avoid all consequences, or at least that how it seems from my admittedly ignorant position.