Branching skills are always a false excuse, it's still pretty easy. Say you have a job that has 2 combos : 1 2 3 and 1 2 4. Just consolidate 1 2 3 and leave 4 separate, so that you just need to do 1 1 1 or 1 1 2(previously 4). That already cuts down hotkeys from 4 to 2. Hell, there may even be some plugins that do just that already.
As far as "reverse order", i have no ideas what you'd be talking about, do you have any exemple?
The only extremely niche thing it'd change is that you couldn't just spam 1 2 on some jobs in very specific situation (such as PLD where you could spam Fast Blade -> Riot Blade for more mana regen) and you'd have to commit to the full combo.