In a (not-so-distant) past life I competed in a road rally competition for alternative fueled vehicles. Because this was a "rolling tournament" all teams were required to send at least one team member per day to volunteer with the organization to keep things running smoothly. We actually sent 2 or 3 since our team was kinda big (10-ish members)
Requred volunteering hasn't really been neccessary in the past with
FIRST (which I was shocked to see the number of volunteers who showed up to events without being required to sign up when I first joined in 2001) but with an ever growing schedule & more events added every year, this could be a solution.
If teams are tight pressed for members, exceptions can be made, but there are certainly plenty of teams who bring a huge amount of people who are just filling stands, who would actually have some fun volunteering.
If Michigan approached every team & told them (re: requested very nicely

) that they had to supply 1 member for every 10 who show up to compete, I'm sure teams would happily agree, and if not, too bad.
It's in the rules. lol
If a team brought 100 people, I'm sure they could spare about 5-10 for the weekend to help out on top of the already teamless, or regular volunteer crowd that show up.
Volunteer Co-Ordinating would be much much crazier, but we should expect that if we change up tournament structures this drastically in the future.
From someone who has volunteered at countless events since 2001 in FLL, since 2006 in FTC & since 2004 in FRC, I can say that being part of the volunteer crew is both fun, rewarding, & gives you a different perspective than just going with a team, & can let you "learn the system" a little better which can help any team in the long run during a weekend filled with a lot of commotion (and especially for the rookies) who have a lot of questions.
It's also easier to understand
WHY FIRST does things when you're on that other side of the fence between competing & running/volunteering at an event.
Let's face it. Without the volunteers that dedicate their time (in the weekend of an event alone - not even counting all the behind the scenes work all year long) an event would never be as fun, or sucessful as they have been all these years.