Breakthrough Casual is a good mode but it ends too quickly

I disagree.  While yes, attackers will also kill any bots they come across, I assure you attacking players are also trying to capture the objective points.  However, it is much more difficult for attackers in Breakthrough Casual compared to defenders because bots make for poor teammates when trying to capture points.

We see this in many games, not just battlefield, where the defenders have an advantage.