Focused, and ready for action.
Throughout the series, Kenshin has suffered pain, and then more pain at the hands of Kaoru. This pain is not direct, but indirect as the worthless bitch gets captured over and over again, and then needs to be saved again and again. Had Kaoru been destroyed early on in the series, many of Kenshin's wounds and scars would never have had the chance to appear. Not only would he not have to have gone on so many pointless missions, his mind would be more clear, and more focused. Every time Kenshin is about to fight an unavoidable battle (many times because of Kaoru), the bitch always has to yell or whine, or get in the way in some form. Kenshin loses focus, and then it's another scar to add to the collection. Examples include battles between Kenshin and Sayo's brother (Sayo rules) and Kenshin and Saitoh. Even in the VERY FIRST episode Kenshin had to save Kaoru! Kaoru always gets into the way. If Kaoru has been smashed early on in the series, perhaps sometime after they met Megumi, many things would be better. By then Kenshin was very good friends with Yahiko and Sano, and would definately stayed with them at the dojo, or some other location close by. Megumi would be able to get closer to Kenshin, and thus deliver more prompt medical service. Sano and Yahiko would move in with the show's hero, and the storyline would go on from there. Everything would be better from there. Kaoru would not need to be captured, and Kenshin could fight knowing that all of his friends were safe. Focused and ready, we would see a better warrior.