Ability damage was one of those 3e mechanics that read really well, but played incredibly poorly - because changing an ability score meant there was a cascade of changes right across the character sheet (and, worse, a 1-point reduction in the score might or might not have any effect), even very low-level effects weren't as easy to apply as they should be.
As I said, in 5e playtest rules it is already better...
5e is not really meant to be based on pre-calculation of stuff as 3e was.
For example you probably won't have to fill a long list of skills scores, but characters are just going to have
one bonus or two at most to a skill, written under the "Class" and "Background" tabs. When there are no such things as ranks, synergies and other mods, then you effectively only have to sum 2 numbers (or 3 if you have a bonus to the same skill from both class and background, assuming they stack). Thus you don't pre-calculate skills, you just add ability mod + eventually your single bonus
during the game.
Spells DC are always 10 + ability modifier, you don't even add spell level anymore.
IMHO, not only we don't need a skill list but
there isn't even a need to have an entry for Initiative and spells DC on your character sheet anymore. In the case you have a special bonus on them, only then you mark it on your character sheet (just like you mark skill bonuses), because Init = Dex and spells DC = 10 + spellcasting ab. It's too easy to remember or calculate on the fly to even waste a line in the character sheet.
Saving throws are gone. Since they're just ability checks, all you need to know is your current ability score. Double the columns for ability scores/bonuses, one for full-health and the other for current value.
Even HP aren't that big deal because now it is the Constitution score applied once, not the Constitution bonus applied once per level, so if you're drained 5 points of Constitution, then it's -5 HP (although they could rule in 5e that HP are not even affected).
The only big problem left are attacks and damage (and to a lesser extent AC. This is indeed potentially a PITA in case you are drained in the ability you actually use, although once again the worst calculations of 3e are absent (like x1.5 Str bonus to damage).
I think that all this is far less complicated than in 3e...
But if they wanted to make it even simpler, they could just avoid ability damage/drain happen during combat. That's really when it hurts to make the calculations... But if they use ability damage/drain only for poisoned traps, disease, curses OR in case of monsters ability making the damage/drain trigger after a couple of minutes (thus presumably after the combat) then it's even easier.