The reason why SWAT is being overused is complicated. On one hand, so much pointless stuff is illegal, using SWAT expanding as a futile way of increasing force to stop black markets that cannot be controlled. On another hand, the military industrial complex is the biggest business in government. It influences just about everything in our lives. I see all of the social "wars" as offshoots.
Specifically, in this case the"experts" and gear manufacturers get paid when SWAT tactics are used more frequently. Both of these create a system that is very hard to reform because of the special interests involved. If we reduce the number of laws, that eats into paychecks. If we restrict the use of SWAT tactics, that eats into paychecks. More government "defense" spending means more laws, leading to more SWAT and more jobs.
The cure is less government on all fronts. We need less spending, less laws, fewer public jobs and no public sector unions. We also need some SWAT, because sometimes that is what it takes to get the bad guys. So, rather than focusing on SWAT maybe we just need to focus on the government that creates the environment where the mission of SWAT can creep.