Old school D&D players are often accused of being against even “obvious improvements” to D&D rules like unified experience tables and ascending armor class. Often the reason they are against a “obvious improvement” change is assumed to be something like blind stubbornness, nostalgia, or some other equally “irrational” reason.
While it is true that some old school players reject all such changes out of hand because they are “different”, many player reject some such changes because they end up changing game play in ways they do not like. These unintended effects that come with some of the rules changes that modern players often think are irrationally rejected are what actually cause many old school players to reject them. What appears at first glance to be a minor or even cosmetic change actually ends up having effects that make old school style play harder — which is the real reason many old school players end up rejecting the change — even if they are not good at articulating those reasons.
For example, more than descending/ascending numbers actually changed with the switch from descending AC to ascending AC in WOTC D&D. With descending AC, the game rules greatly limited the bonus applied to the to-hit rolls — modifiers more than +20 or -20 were generally confined to the worst of Monty Haul campaigns. Once the switch to ascending AC was made, all limit on bonuses seemed to disappear which tended to make playing real “old school play” hard. While this is a separate issue from ascending AC (as games like my Microlite74 show one can have ascending AC and limit bonuses to TSR era levels), it is not immediately obvious that it is.
The change to 3.x style saving throws had a similar side-effect. While the three saving throw classes might have been accepted by many old school players if the saves otherwise worked like TSR D&D, the changes that went with the new saving throws made things like saves versus magic harder if one was saving vs a high level caster broke many old school assumptions (e.g. that a high level character — especially a fighter — had the same great save vs spells whether the opposing caster was a first level magic or Elminster himself). Those side effects had major effects on play — helping to create the godlike high level casters.
One of the things that would make using one unified XP advancement table unacceptable to many old school D&D players is the expectation that all characters in the party need to be the same level all the time which seems to come with it. This silly (to the old school mind) meme seems to have become the common expectation with 3e — when the single unified experience table appeared. If you can’t have the single XP table without many players — and lazy module designers — expecting the party to therefore always level up together/always be the same level, then many (perhaps even most) old school players will reject the single XP table idea because it ends up changing the game in ways they find unacceptable.
A single XP table also changes the way designers tend to construct classes. Old school class construction tends to be “organic” in that one writes up a list of things the class should be able to do in the campaign world and designs the class around those abilities with little regard for level by level balance with other classes. When the class is designed one then looks at it in comparison to the other classes and creates an XP advancement table (and — if needed — some class limitations) so that is is somewhat balanced vsrsus other classes across the campaign. When there is a single XP advancement table, class design tends to change as a level by level comparison of the new class to other classes as people tend to feel that classes should be about as powerful at the same number of XP points. While some people think the new school style of level by level balance is better than the old school “across the campaign” balance, there can be no doubt that classes are designed differently old school vs new school an that the way XP advancement tables are handled in the rules contributes to this difference.
So next time you think people who prefer older and less intuitive rules to newer and supposedly “better” rules are simply being blind or stubborn, look beyond the actual rule to possible side effects of the rule. It’s possible that there are less than obvious side effects to the new rule which result in changes to game play that make the style of play the objectors enjoy harder to do with the newer and “better” rule. The new rule may indeed be better by itself, but its side effects may simply be unacceptable to the “old school” style of play.