Playing aggressively is OK. Being offensive is counterproductive for the team, period. Apparently Riot tracks game outcomes and correlates the win loss percentage with reports of offensive behavior toward teammates. Games that have good team dynamics (no trolling/flaming of teammates, etc.) result in a higher percentage of wins.
And from what Riot is saying, what I think you are calling "playing aggressively" is an anomaly, relegated to infrequent outbursts on a "bad day" potentially by any player. A profile system wouldn't account for this one-off behavior because it is so intermittent and rare. That being said, if you did implement a profile system, would a flamethrower wielding troll with a hair temper want to play with 9 other similarly foul tempered combustonauts? That is an interesting question, and I think the answer is no. I can even imagine the game devolving into a chat room, with everyone so busy insulting each other they hardly even play the game.
I have played LoL for quite a while and the efforts they have made toward improving player conduct have had an undeniably positive effect on the game experience. Are there times I would like to unload with both barrels on a teammate? Sure there are, and I actually have. However, with the reward system, the player-run Tribunal punishment system (I have never been banned or even reprimanded BTW), and Riot's conveyance of the idea that cohesive teams result in better game outcomes, the knee-jerk reaction to flame someone is tempered and delayed enough to permit a different decision tree to be considered.
So instead of the usual flame related decisions ("Hmm which would be better to use? Talk about their mom, insult their sexual prowess or orientation, or go for the nuclear option and blast them with n-bombs?") the thought process is subverted to "Should I encourage them, provide positive constructive criticism, make suggestions on team oriented strategies to prevent the same problem, or just let them and the team know its OK and we will recover." This is good thing.
In some ways, their efforts to use social engineering with a reward and punishment system have made me into a social engineer as well. I look for ways to elicit positive responses from other players that will result in Honor rewards for myself. I also look for opportunities to make bad situations better, make good situations great, and generally help my team with the words I use. Does the team need a leader? Well then I step up and with positive encouragement and proper deference assume that role. Is there a possible conflict developing on the team between players? OK, what can I do to put myself in a position to neutralize that conflict to ensure the health of the team dynamic?
In summary I will say that their in-game controls have resulted in a much better gaming experience for me and many others. I commend them for their efforts and as a direct result of these efforts I will continue to spend my hard earned coin on frivolous skins, buying champions, and other assorted digital trinkets they offer in endless profusion and permutations. Looks like Riot has revealed in this story the step just before 3) PROFIT!