Community Manager Josh Nash explains the importance of why replays do not include the chat logs.
Blizzard already has access to the chat logs and will use them to determine when a player is being abusive. We have seen this demonstrated in the past:
In short, we as players have a responsibility to be a positive member of this community and to report players who do not follow the Blizzard Code-of-Conduct, however it is not our place to try to take matters into our own hands. Doing so, can cause players to be bullied or shamed from playing the game when in fact they are not the ones that are truly toxic. Remember that nearly every player gets reported at least once, however only about 1% of the overall Overwatch community is consistently disruptive. (Source: Fair Play Alliance) We all can have a bad day (I sure know that I have had a few) and Blizzard’s actions are structured to give players a strong opportunity for players to correct their behavior. Remember if you do see someone being disruptive, Report, Block, and Avoid, but it is best that after that encounter you should take a small break, and move on and prove that you can be better than them by staying positive and friendly in this game.
Play Nice, Play Fair. (^^)v