Sorry - my post was confusing in hindsight. I am suggesting that the SM enlist adult volunteer support for uniforming - not necessarily that all the adults uniform.
As Scoutmaster you want adult support for transformative decisions. Yes, we'd like to think the adult volunteers will support the Scoutmaster, but it's still important for the SM to get folks behind a big decision. Going to a leaders/committee meeting and having a frank conversation about supporting this decision is helpful. That helps ensure that word gets around. It also helps that leaders encourage their own kids to uniform as well.
Since you brought it up, I'm in favor of adults feeling empowered to uniform. Scouts notice ASMs and see what they do. So, if the Scoutmaster is saying "uniforms are important", but the ASMs are out of uniform or poorly uniformed, that's noticed.
On the other hand, if the adult treasurer, advancement coordinator, committee chair, etc. are uniformed that sets even more examples. If I were SM, I would ask, the ASMs to uniform if possible. I would encourage the committee members to uniform if so inclined. We have many adults who show up to meetings in uniform (and most do not have beads). There are othet subtle benefits.
Adults seeing other adults in uniforming encourages volunteering.
It helps committee members feel a closer connection to the troop.
It makes it clear to visiting families who they can approach for questions
In an era of needing more registered adult supervision, it helps everyone know who the registered adults are.
It's not uncommon to have 10+ adults in uniform our typical troop meetings - more at a COH.
BTW - yes, we get good participation from Scouts wearing uniforms. We've never needed to do a uniform inspection to encourage that. We rarely even have to say something to a scout.
Here is where I disagree with @ParkMan, the SM was the only adult who wore a uniform in our troop. The rest showed up in their best work clothes. The ASM who was a coal miner looked pretty rough, but one of the most caring men I had met in scouting. I never saw a committee member in a uniform until my sons joined scouts. Still think it's dumb. Why does an MC need a field uniform? To set off his/her beads?
None of those adults bothering with uniforms, and guess what? I made a point to look sharp every meeting and hang my pants creased in the evening. Shoes polished every Sunday. Inspected patrols every couple of months just like the SPL's before me had done.
You're the only adult who the scout needs for an example of a sharp uniform. You don't need your adults to uniform. It's not their program. You need them to admire your scouts. You need them to be kind to one another. You need them to turn into wallpaper as the scouts run meetings and activities.
I would encourage you to start with setting expectations about uniforming. When you become Scoutmaster, make it clear that you expect uniforms to be worn to meetings. This is a simple act that as Scoutmaster you can easily push for. When you become Scoutmaster, people will expect some amount of change to occur. New guy, new rules. So, take advantage of that.
Of course, start it within the adult team. At a meeting, let the adults know that you want uniforms to be actively encouraged. Explain the reason in a way that is similar to what @qwazse did. You are doing this because taking pride in how they wear the uniform leads to Scouts taking pride in themselves as people. Don't put it in terms of benefit to the troop - that's irrelevant. Don't threaten with Scout Spirit rules and preventing people from ranking up.
Once you explain it to the other adults, then go to the Scouts and their parents. Explain that this is new and that you'd ask the parents to support and encourage the Scout on this.
After all this - then simply encourage. If a Scout shows up without the uniform, ask them in a pointed way. "Hey Bob, why arn't you wearing your uniform this week? ... You forgot? ... Please remember it next time."