Actually, lower the pokemon's defense in the first and second generation DOES increase the catch rate. I got an original Pokemon Silver for Gameboy color for Christmas, and I just caught Lugia today.
I nearly spent all day trying to catch it just by putting it to sleep, and dropping the HP. I spent 33 Great balls trying. One the second try of lower it's defense stat, all it took was 3 trys with Fast Balls.
In conclusion, lowering the defense stat with moves like LEER, does help your odds of catching wild pokemon.