So, the button merging feature... did I get this right?

[PyurBlue]

Yeah you're right but those optimizations are so minuscule that a single extra crit would triple the combo optimizations gain, specially when the bosses are like 9 minutes long, I think the 1 button combo that can't ever be failed would outweight it on the long run.
I would rather pvp combos for weaponskills just don't exist and everyone plays on the same leveled field, a few specific abilities having a 1 button combo seems like a fine middle-ground.

The gain isn't a lot but I was trying to point out that there are benefits to breaking combos. Fight design would also influence how beneficial combo breaking is. The situation will never come up in single target fights but that could be solved by adding more enemies to fights, specifically more duo enemies since the AoE threshold is usually three.

I don't mind an autocombo function existing as an option, but it's not something that I'm interested in using.

It makes more sense in this situation to swap to the target with higher health with your combo finisher.

I was keeping things simple to avoid a long post. The enemies could be separated in a way that prevents switching target, such as one casting invulnerability on the other or large physical distance that prevents the use of gapclosers.

Resource gains also change the optimum but they may not exist in all cases.

Why would you not want to build resources?

Resources weren't part of the example. They could make it more beneficial to finish the combo, but the combo in question or the situation in which it is in use may not involve resources in the first place.