kenjib said:
1e - To simplify combat to a very simple, story based, hit-hit-hit-done combat we do the following:
1. Remove re-rolling initiative every round: Negligible impact on other areas of the rules.
2. Remove weapon speed: Impact on interrupting spell casting. Negligible impact otherwise.
3. Remove armor vs. weapon type: Negligible impact on other areas of the rules.
4. Remove miniatures: Negligible impact on other areas of the rules.
Except you have now made movement rates useless and lots of rules are addressed to the question of how fast PCs and monsters can move (such as the armor rules and encumbrance rules), and you still haven't addressed unarmed combat. What if a player wants to knock over an opponent (by overbearing him), or grab and opponent (grappling him), or even just hit him with his fist (pummelling him). Now you have a massive headache.
Removing miniatures or some other method of determining placement has massive impact on the rules: specifically how do you determine who is in or out of an area of effect for a spell? How do you determine who is within visible range of torchlight or infravision and who is not? How do you determine if a thief can backstab an opponent or not? I think that in your rush to "prove" how easy 1e is to modify, you rushed past some pretty important considerations and relied upon your (probably almost unconscious) familiarity with the rule set to mentally smooth over these and other areas that need to be addressed when you make the changes you suggest could be made.
Changing 1e
is much more complicated than you seem to think, but you don't notice it because the system is so familiar to you.
Now let's look at 3e. What are some things that we can do to simplify combat?
1. Get rid of Aoo: Impacts interrupting spell casting, spell-like abilities, and some extraordinary and supernatural abilities. Impacts fleeing and pursuit. Impacts flanking. Breaks disarm, grapple, overbear, sunder, and trip. Makes several feats much less useful or broken in some other way.
These problems are no more complicated than they would be in 1e. You suggested coming up with a house rule to cover interrupting spellcasting in your assortment of 1e "fixes". Now that it comes to 3e, though, this is a big problem? Eliminating AoO's has little impact on fleeing and pursuit, it just puts you back where the 1e/2e rules were. Just disallow disarming, grappling, overbearing, sundering and tripping, this puts you back to 1e's version of combat. Simple fix. One easy option would be to disallow some maneuvers for anyone who doesn't have an appropriate feat, and just disallow others.
2. Get rid of miniatures, and simplify the movement system: Requires a complete re-working of flanking rules, requires a complete re-working of the action system (which is very foundation of a very large percentage of the game mechanics), impacts all situations involving threatened areas and those that rely on these rules, impacts concealment and cover rules, impacts attacks of opportunity, makes several feats very difficult to work with (e.g. Spring Attack, mobility).
These issues are no more difficult to resolve in 3e than they are in 1e when you get rid of miniatures in that system. Getting rid of miniatures requires you to ignore the movement rules in 1e, requires you to figure out how to apply the thief's backstab ability (and possibly the assassin's assassination ability). Since you got rid of AoO's, you don't need to worry about threatened areas, so that isn't any kind of concern now. And since 1e did have rules for concealment and cover (albeit ones that were somewhat obscure and not well placed in the DMG), these issues are no more or less difficult in 3e than they were in 1e.
In addition, we have a 6 second combat round, so whereas in 1e where we could just assume that all of the maneuvering, fun theatrics, and tactical positioning, and such were done as part of that round we now have to manually hand all of this with mechanics for each action and theatrical flourish. If we want to extend 3e rounds to 1 minute we break the entire action system and distort time in numerous and unforseeable ways.
And this explains why there is a fair amount of detail in the 1e rules about determining and using movement rates. The 1e game was a very miniatures friendly game, it clearly showed its wargaming roots in this regard, and most of the complaints you have about eliminating miniatures from 3e apply with equal force to eliminating miniatures in 1e. Sure you
can with 1e, but the modifications and gap fills that you used to do so have likely become so ingrained in your mind that you don't even notice using them any more. And the ease of doing so with 1e is not really any greater than the ease of doing so with 3e.
Easier? I think not! In both editions you have to modify caster interrupting rules. Other than that, it's all about wrestling with 3e.
I think you are looking back with rose colored glasses and not really focusing on how many things need to be changed by the modifications you propose for 1e.
) But the good thing is that when the get to 6th level, the can just plug their Characters into the full version and off they go. 
