Of course there were more late round steals back then. 20-25 years ago there wasn't nearly the coverage and publicity surrounding the draft that there is now. Fans didn't read scouting report upon scouting report from internet guru's like they do now. There wasn't as much film watching by fans and draft guru's, they didn't have entire shows specifically for draft talk, there wasn't the news technology there is today... I could go on forever.
In this day and age, 2009, it is almost impossible for a player to fly under the radar. Sure there are players here and there, such as a Marques Colston, even Tom Brady. But as a whole, it was much easier for that to occur back then. Now, it is nationally publicized about what your 7th round draft pick ate for lunch.
Just different age and era. You're not going to find the consistency in late round steals per team that you did before.