Is it possible for non-essential USMC personnel to get their jump wings?

Well first off that's not our job, we take the beach and the Army jumps in after we secure an LZ. Most of the Marines I knew that had jump wings had served with one of the units you mentioned the others were brown noseers that were just trying to make there uniform look cool. If your unit ever has to go to Ft. Bening for training there is a good chance you could get an empty seat in the class. When I was in 2nd LAV BN (now LAR) we did annual training down there. Our C.O. always managed to get 1 or 2 from each PLT into "empty" seats to get qualified.

Not sure but there has always been "Workarounds" that allowed folks outside a Certain Job Field to Gain Qualifications, It is usually a lot more challenging and takes a bit more time but I hope there is a way to get your Jump Wings.

As for jump wings in the Army, I am not sure, people still go in non-essential status much like Air Assault School. Ranger School and other things I know are closed to non-essential as they used to be open for pilots. Maybe someone at the school house will chime in. I am not AIRBORNE even having served for 14 years in the 101st Airborne Division. Does the Marine Corps have its own or do they go to the Army course.

I giggle every time I read someone get but hurt from the non-essential comment. Insecure much? LOL

Technically you don't need the school, you just need the jumps. I was an MP and we had a CO who was an academy grad and he had a another academy grad lined up with the planes for us to get our jumps in. The deal hinged on that air wing unit needing to fly more training jumps. I can't remember how it all fell apart but we were scheduled to make the jumps and rate the wings, without the school.
With that all being said, I don't think I ever met anyone who had the wings without an MOS that required it.

I've seen US Army Airborne wings on uniforms of soldiers of different US Military branches. I've also seen other countries' Airborne wings on U.S. Special Forces soldier's uniforms. First off - anything is possible...but my guess is that unless you are in a commissioned, leadership-type position you're chances aren't very likely of landing an Airborne school slot. I've heard some enlisted soldiers referred to as "badge-finders" simply for being interested/curious about various schools. I say go for it, Sarge. Be all you can be. Semper Fi.

I can't say for sure, but I can tell you that I went to Airborne School with two USMC Majors, and as I bounce back and forth between Benning and Bragg, I keep seeing one of them around. He still has his Basic Parachutist Badge, meaning that in the three years since we graduated, he has yet to complete the additional five jumps required to earn his Navy and Marine Corps Parachutist Insignia. This suggests to me that his job doesn't require much parachuting, and therefore Airborne School was not exactly essential for his job.

"non-essential USMC personnel" No such thing.

Thats a marine thing Any can go to Jump school but your command has to make the decision if its worth the Money they are going to spend to send you...

Best chance to get that is to go to JCSE at MacDill AFB. What the heck is that you ask? Joint Communications Support Element. They have jump slots. If you’re a Marine and not qualified to jump and in communications, try for this assignment. Many of the Marines I know retired as SgtMaj because of this assignment and getting the school.