Nothing else needs to fit, though; it has incredibly few ST weaponskills compared to actual "combo" jobs.
At present, there is no reason in real content to ever hold Refulgent Arrow. That disappeared with Barrage itself granting RA. You could easily have HS replaced automatically by SS (later RA) and BS by RA whenever the latter is available.
There is no longer sufficient difference between VB and WB to make their order matter, nor does either button have any reason to exist once first applies, following the addition of Iron Jaws. You could easily just use a target-conditional combo there of WB->VB->IJ.
Though 98% of the time in any more serious content we will strictly follow the order of WM -> MB -> AP, there is no need to set them into a combo.
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The real question to me, though, is why we don't just let players set these combinations as they please.
Drop the "combo" trap (combo skills being usable instantly, but for virtually no effect / only as a trap), perhaps don't let skills like Iron Jaws be cast without an effect on the target, and only let the first applicable line queue if we really don't want too many actions in the stack, but there's no reason to have stuff like RDM's melee combo or MCH's, GNB's, or DRK's 123 cycle, etc., each on separate keys. They've zero points of decision within those combos.
