I'll have to slightly disagree.
Certain occupations are a young man's game. And it may be hard to break down by MOS/career field who would "qualify" for the 20 year retirement as opposed a longer (say 25 or 30 year retirement). I'll use my career field as an example.
I was an MP in direct support MP company. We were expected to be engaged with the enemy. In fact, in Iraq, some of the highest causalities were in MP units (and Transportation units), Occupations that are supposed to be "In the rear with the gear." Given today's non-linear battlefield, there no such thing as a "safe" desk job. (Yes, the POG's got mortared and did take casualties, not as many as the grunts, but some).
Even when I was in, my second Platoon Sergeant had spent his entire career (up until that point) working Garrison Law Enforcement. He had never been issued TA-50 in 18 years of service !!! Yet he was an MP. (As a point of interest, the two soldiers from my former unit, that were killed in DS/DS, were both females).
Yes, the 20 years is a throw back to when as an enlisted man you spent twenty years out in the west chasing Indians.
* Twenty years, even now, is long time in a job that demands you 24/7/365. It's not like other jobs where you go home at night (or if you travel, on weekends). Plus, you don't have much say in where you live, or how long you'll live there. There are year+ long deployments. Then there's training cycles. I remember spending 4 months sleeping on a cot in a GP medium in the tent cities at Grafenwoehr and Hohenfels. 3 months of living like Gypsies during REFORGER's and CARAVAN GUARD's (Then another 3-4 weeks of playing Uncle Sugar's bagman to pay for Maneuver Damage. But at least we could stay in Gasthaus's.
)
So, it's not all desk duty, because even the clerks and jerks went with us when we did Gunnery and field exercises. (If anyone should get full pay after 20 years it's the cooks. Those folks got up hours before to get breakfast going and stayed up hours late so we could have mid-rats when we were running 24 hour ops. Even in Garrison we had one mess hall that made mid-rats for all the folks pulling 24 duty. (Staff Duty, Charge of Quarters, MP's, Medics, etc.)
The current system seems to work pretty well 50% after 20 years (did I mention that you are still subject to recall after retirement and the UCMJ applies also?. Yeah, there were thousands of retirees recalled for DS/DS. Not sure how many for OEF/OIF), then it incrementally ratchets up to 75% if you stay for 30. The pogues that get out at 20 are generally at the E-6/E-7 or O-4/O-5 level. (for those keeping track at home it would be mostly CW2-CW3 also.)
The goal being you want to keep some of your experienced folks around to teach and train. My first PSG had been a E-nothing in Vietnam. That 18th MP Bde BTDT patch on his right shoulder made our troopies sit-up and pay attention to what he said.
Cops and Firefighters. 25 years or age 50 for patrol/non-officer positions. I don't want the guy that's dragging me out of a burning building to have a grabber and we both become crispy-critters. Same with cops (who should have to pass an annual fitness test.) I want them to be able to run down Sumdood who tried to break into my house. But after a certain point, you should be out there on the streets. Maybe stay as a Detective or Battalion Chief.
25 years for 50% pay seems about right. And no going back and double dipping, both military and police/firefighters.
*- The phrase "He bought the farm" came from this time. When after 20 years of eating dust in west, you would retire to back east and buy a farm to get married and settle down.
