Older shooters were much faster paced than the typical FPS these days. Combined with laser accurate weapons, death came swiftly to the weak.
I'd say the younger crowd is the one lacking. The only way they know how to play is with shields, auto-healing, leveling, and unlockable weapons rather than tactics, a handfull of weapons, and pure skill.
Sure their reaction time might be a tad faster, and they learned how to swim in a game world full of vehicles, new game types, and voice coms, but experience trumps speed any day of the week.
I loaded up the new Alien vs Predator demo and was smoke checking the nubs within a few rounds. A few rage quit, and a few asked how I was beating them so easily on a brand new game. I simply pointed out that I've been playing this same game in one form or another for more than 10 years.
Dump me into any FPS and within a day or two I'll move up to the middle of the online pack. You only end up at the top with lots and lots of practice. Unfortunately real life calls, whether it be work or the family so most of us over the age of 25 (me I'm 38) don't have the time to play.
Let me predict something in 25 years or so, when the first generation of old school FPS gamers retire, a great wailing will fill the voice coms, of "How the heck did grampa and his gaming budies mop the floor with us again?!" and our response will be "Because junior, we were learning how to rocket jump before your daddy was even a gleam in my eye."