The reason they where so feared in 1e was simple , HIGH Magic Resistance (MR), I think it was 30% and went up 5% for every class level they had.
They always had female clerics with those damn tentacle rods and most of the males happened to be fighter/wizards.
So you had 5 or 6 front line guys keeping you busy while clerics and wizards in the back blasted you with spells. They would fireball or lighting bolt you (or worse) and not worry about hurting there own guys because they hardly ever where effected by any damn spells! Also with the darkness they had, and there ability to fight in the darkness, it sucked even worse!
Females could use charm person as a inate spell ability and because 1e charm was a damn 1st or 2nd level spell that works like a 3e Dominate Person you where in a world of pain my friends!
Damn Drow!