If you run the state qualifying time, you don't have to run either districts or regionals. People will sometimes sit out of regionals to save themselves for states or run different events as either a workout or to qualify in more events. The thing you gotta remember, though, is that the state qualifying time is the average of the sixth place time at states from previous years. If you can run that, then you're quite good and should be able to place at states. It's not just an easy time that anyone can run. Very few run the time. This can open up spots for runners who would not necessarily be in the top 6 at regionals if everyone was forced to run, but that really only adds a few extra runners at most to an event at states (seriously, many regions don't have an athlete with a state qualifying time, so we're talking at most maybe 3 extra participants in an event at states).
You can't run the state qualifying time in a dual meet. It has to be an invitational or districts/regionals. Thus, it'll be a meet with a lot of teams, state officials (or another state's officials if it's not run in VA), FAT, etc (there are actual rules, but I don't know them off hand). Most teams run an invitational almost weekly during the season up until districts. You can run the district qualifying time at a dual meet, I believe, but that's it.
Personally, I love the system. Different regions in VA are drastically better than others. A qualifying time ensures that all the best athletes will be at states and athletes won't be penalized for being in a stronger region or having an off day at regionals.
And this may sound like districts and regionals are less important, but teams still want to win team titles, not to mention athletes wanting to win individual titles, and most athletes with state qualifiers will run something at these meets to help out their teams.