I think you're getting swayed by big names. Most of the time, older players (over 30) have had skills decline, so aren't as important, so are not as noticeable when they miss time due to injury. There are fewer older players who are still superstars, but lots of older players in general who get injured; odds wise, injuries more likely hit the lesser known older players than the superstar older players. Additionally, upon receiving a major injury, older players kind of just disappear quietly into the sunset so we forget they were injured.
Mourning hurt his knee last year and hasn't played since. Pollard hasn't played since his injuries last year. It happens all the time to older players but it's not as reported or noticeable because older players are often less important players.
In '07-'08, the Spurs had the Oldest Average age on the team at 30.6 years. Portland was youngest at 24.06 years of age. a quick look through the data suggests that the average age of an NBA player is around 25.5-26 years. Since it's nearly impossible to be in the NBA at the age of 19 any more, that means that for any player 32 or above there must be multiple players under the age of 26 in the League. This is a round about way of saying there are a lot more "young" players in the league than "old" players.
Therefore, if injuries were equally likely to occur to any age group, we would obviously expect more injuries to young players than old ones. However, taking a quick look through the NBA.com injury report shows a lot of "old" players with injuries, but many of the "old" players are no longer such important players, so their injuries are not as exciting or as media worthy. In addition, a few of the injuries are to players who haven't played this year, which is why their injury status hasn't generated the same news as the injuries to young players.
So, considering that:
-there are fewer old players in the league
-there are still fewer "old" players still playing at a very high level
-younger players generate more news than older players
it seems very clear why it APPEARS as though injuries happen to young players more frequently. However, after looking through some data, I feel completely safe in my previous statement that:
-Older players are more likely to be injured than younger players
-Older players have longer recovery times than younger players.