This is a good base for bruchetta recipe but there are a few things that are missing or can help make it better.
First off, a little sugar really brings out the flavor of the tomatoes. Seondly I add a swirl of balsamic vinegar. I also sometimes add capers in for a nice touch. I also use a shallot instead of onion but either is fine.
I do think it's important to toast the bread before putting the tomato mixture on there, otherwise it's too soggy. Just drizzle some olive oil on there and salt an pepper and then toast for just a few minutes. Gives it a nice crunch.