My original intention was to examine whether 1st ed AD&D was a harder game, compared to 3rd or 4th edition.
I've been playing a 1st ed game for the last several months and wondered why it was so easy for player characters to die, even with a DM who normally isn't a hardass or heavy handed. (My 1st ed AD&D DM does his campaigns in a "Monty Hall"-ish manner and tries to avoid deliberately killing off players and TPK's. I've played previous 3rd and 4th ed D&D games with this same DM).
With the exception of the fighter/paladin/ranger matrix, the monsters' base level attack bonuses scales up faster than the players' base attack bonuses as the levels go up. This may partially explain why some low level characters die so easily.
The retro-clone remark at the end, was an off-the-cuff remark.