I think it was important to humanize Kyle to the jury. The majorly female jury btw.
And what image do you talk about? The shitty one or the absolutely shitty one? Or the shitty one with poorly established relevancy? For fuck's sake, the prosecution is playing poker with only two cards in their hands and one is from Uno.
The quality of a defense is not measured in the OBJECKSHUN YURR HONORs by the minute. For instance, objecting too much during Kyle's cross (while he took every hit on the chin like a trooper without flinching and marching on) would only made it look like they use it to help Kyle like he was a puppet on strings. They used it here and there, gave Kyle a little breather to compose himself, but Kyle still managed to win that battle on his own. He's very young, he did very well and the prosecution got nothing out of him that was more significant than "Hurr, he told some rando on the street he's an EMT when he's not durr".