My only experience with 1st edition D&D is the Curse of the Azure Bonds CRPG. I played PnP RPGs at the same time but not D&D. My impressions was that it had fun combats if you played all characters at the same time. This was due to the following:
First of all, thieves were worthless in combat. Due to the fact, though, that multiclassing was imbalanced you never had to have a pure thief, you could always multiclass it with a fighter. You had to be a dwarf, though, because of the level limits for demihumans. Being a computer game, you couldn't houserule the limits away (who would want to play a half elf? Max level 4-6 in all classes except thief, the class that sucked).
This meant that playing a pure thief in a combat heavy dungeon must have been extremely dull. When I read about people here talking about guarding the back door or whatever, I can't imagine why you would want to do that.
Second, fighters were very durable and the work horse of combats. They could fight all opponents, even the ones with Magic Resistance. The problem was that all their attack options were... attack, more or less. They were good for mopping up opponents that were too weak for the magic user to blow his spells on. This made sure that the fighter always had something to do but unless you cheated the strength up to 18/xx the damage output was frustatingly low, taking an eternity to kill of a pack of weak enemies. The ranger and paladin were essentially the same. The solution here was, again, to multiclass, this time with elves. They were a bit shorter on HP and THAC0 but those extra fire balls sped up a lot of encounters. With the help of mirror image and stone skin they became flat out better than pure fighters at doing what fighters are supposed to do.
Clerics were batteries of healing and hold person. They were integral, anyone in the group could die in a given location but if the cleric died you had to leave. There was no chance to play that game without a cleric. The problem was that the cleric had abyssmal damage output and when you could prepare other spells than healing the spells (except for hold person) often were very boring.
Wizards were the heavy artillery but only used in very dangerous combats. You couldn't waste attack spells on 75% of the encounters so the wizard generally just hung back in a corner. After I while I didn't even bother to use them for attacking with slings since the damage output was too low to be worth the time.
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To make a long story short, I can just imagine how dull the fights must have been from a tactical POV if you played just one of those characters if you didn't multiclass. I played another PnP RPG at the time and I wouldn't consider in a million years to switch over to ADD 1st or second edition, since with the RPG I played my group could have the same stories and intrigues while at the same time not having to play a character whose purpose in combats was to "guard the back" or to be a healing battery hardly capable of mopping up ogres at lvl 7.
I don't think I'm the only one like that; I think many players can be won over from RPGs where everyone contributes to combats all the time (like Runequest). To win these people over a very good start is to make everyone being able to do something in all combats. I think D&D 3e did a very good job with this, winning me and my group over. It seems like 4e is about to do the same while at the same time being more stream lined.
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Hmm, that was long and maybe strayed from the topic but I just wanted to add the POV from someone who got converted to D&D because I found 3e to be a fun game, not because of great wheels or a 30 year old legacy. It also explains why at least I like abilities like the one described.