Back in the day (OD&D and AD&D days, that is), we took it for granted that combat tables were necessary. And how could it be any other way, really? Seriously, how ELSE were we supposed to hit a monster clad in chain mail armor? It was how we did it...
But combat tables were a pain in the ass, too. We got good enough at using them, especially if we had the excellent DM's screen to guide us through the exercise (it also saved much wear-and-tear on the Dungeon's Master's Guide, which was a nice bonus).
Hey, fight enough foes and you'll practically MEMORIZE the tables, at least it'll feel that way. But it STILL bogged things down.
This approach wasn't inevitable, however, and other systems were already experimenting with something much faster. And to be honest, table-less combat should have been GROUND ZERO for RPGs...
DISCLAIMER: I understand that things also tend to become better consolidated and streamlined over time, and highly suspect that the general clunkiness of early D&D stemmed from its evolution out of historically accurate war-games. But I wonder.
In a hypothetical, ultra-simple game using only 1d6, combat could be resolved as follows (a chart, yeah, but you could memorize it with absolute ease, and NO ONE would have to read it ever):
ARMOR WORN* 1d6
Light 4 or better
Medium 5 or better
Heavy 6 or better
*Or its equivalent, per the referee. Oh, and you could use this for Pits & Perils, but it'd actually be MUCH MORE complicated!
Now the above table doesn't take into a magical armor, and damage is assumed to be 1d6 across the board, but it works. Moreover, it represents what would be the simplest and ground-level approach to combat resolution. And I sort of wonder why it wasn't.
Oh, and then there's Rolemaster, with a separate table for each weapon (luckily, optional), which makes me wonder if these guys had girlfriends during the 80s (that's a JOKE)...
Enter 2nd edition and THAC0 (To Hit Armor Class Zero), which benefited greatly from an intervening decade of gameplay and seemed to recognize this problem. Their solution here? List the number needed for an attacker to hit armor class zero, which varied by class and level, and subtract the target's armor class to find the number needed to hit. This was chart-less, alright, but it required calculations, albeit very easy ones, to use at the table.
This was a nice evolutionary step, and I imagine the designers felt like it transitioned nicely from AD&D by retaining the original armor class values. But it defeated its purpose ever so slightly by requiring internal calculations, which slowed play somewhat.
Finally, 3rd Edition D&D decided to make armor class a target number on the roll of 1d20, which tells the whole story up front and with minimal fuss. What do you roll to hit AC 16? Uh, 16...
Now, intuitively, things start out easy and become more complicated over time. But D&D almost seems to have evolved in reverse in Benjamin Button style. Once again, probably because the original war-games were generally simpler, and D&D, out of necessity, grafted on more details (and more complexity) from the start.
We'd LOVE to hear everyone's thoughts on this particular issue...