Honestly, there is absolutely no point having fire for ANYONE other than Admin and SOP because fire spread is off anyway.
Giving people more responsibility like that will just be abused like other responsibilities (World Edit mainly) have been so many times before.
I agree with Ouhai, there’s zero point in anyone other than Nek and the admins having fire, like what would you even do with it but wreck stuff, its just dumb.
Portals to the nether? Fireplaces? Cooked pork? Lighting Netherrack? Light? Mob killing?
They’re a few plausible reasons. Considering that fire-spread is off, it’s not exactly a griefable tool
lighting netherrack is the only one there that might be needed, it can be used in fireplaces.
Speaking of lighting portals, I had this hilarious idea of using the nether as a banishment world for griefers 
lol
OR WE COULD HAVE AN ANARCHY ZONE!!!
Like build a big wall around a large area and say within that zone, anything goes (except banned items)
Or perhaps PvP forced on in the nether!
Maybee just make lava placing Trusted+ cause members still mite greif cause all they have to do to be a member is to sign up on the site
Maybe only certain sections there, because there will be some assholes who just try to kill you, if you go to the nether for whatever reason.
Idea:
Nazi Zombies. 
Im going to make a thread for this… I have ideas >:3
I have no problem with people calling me to light up their fireplaces and whatnot. I still think fire is asking for trouble. If the protection goes down, we might have a mess again. If we do allow fire, trusted+ is the way to go.
I have no clue if this is possible at all, but here goes. What if flint&steel only worked on netherrack, so you can make a fireplace but still can’t grief? Because honestly, lighting my own netherrack would be preferred since I pester mods+ enough as is 
How do you guys feel about Flint and Steel for trusted+?
Fire has been and always will be banned for players under the Mod rank. You can make a Flint and Steel, but it won’t produce fire.
We simply do not trust its use to anyone. If you desire fire somewhere then you need to ask a staff member if they will place fire for you.