There's plenty of reason to care. It's a sign Biden's campaign is not yet effective, and Trump is. While most incumbents don't really step up the campaigning until closer to the election, it gives an idea of the ground they need to make up.
It's also worth considering the Trump has been and continues to be great at campaigning. You can not like the guy, but his ability to get large crowds excited at multiple events per day can't be ignored.
There's likely going to be something that really swings the election still, but hoping a random event helps your party is poor strategy. In Trump's case it's unlikely a poor comment is going to hurt him, like the deplorables or binders full of women comments. Hoping for a conviction to change things is an OK backup plan, not plan A.