I hate to rain on your parade with facts, but here are some relevant facts:
The Minimum Retirement Age (MRA) for someone currently in the workforce is around 57 (or any age with 25 years of service).
Payments don't start until you actually hit MRA.
The average federal worker makes 78K/year (let's not debate this too much, as president Obama is in these numbers).
While you can start payments at MRA with only 5 years in service (woo!) the amount of that pay is 1% of your average salary for your three highest salaried years per year. In other words, you'd get less than 5% of your ending salary (about $325/month).
The person in your example works for 20 years (let's say 18-38), "retires", begins receiving payments at 57 (no inflation adjustments during this time period). Let's pretend that this is the first year they receive payments (they retired in 1995) and that they made average salary ($61,000) at that time. They are now entitled to begin those lucrative payments you speak so highly about... $12200/year.
Your point that they will receive this payment until the end of their life is accurate, and they may receive this $12K/year (which is now adjusted upwards yearly for inflation) until they are 90 years old.