I don’t spam missiles much. I spam Explosion / Barrage / Nether Tempest / Orb, but it’s a controlled spam to the point where I have 2-3 Clearcasting procs so I could do a burst of - AP + Malledict + 2x PoMed ABs + Missiles. And it’s a good damage, enough to land a kill if timed right, especially with Shimmer + Displacement on Missiles to avoid interrupts/connects.
I like that I can cast missiles whenever I want - an option to fake cast and still go some damage. Feels and plays better, imo, that doing the same with poly/ab.
I like that I have a Spellsteal as a spamable utility. It almost compensates for the lack of damage and burst options that Fire has and control that frost has.
I don’t know if the same is good for Arenas, but it works good in BGs and WPvP.
But even with that - I agree, Arcane lacks in damage compared not only to other mage specs, but to other caster too. And it lack in baseline abilities period.
Arcane missles apply constant pressure in a way most specs can’t and at 4 charges arcane blast does a lot of dmg for a spell with no cd. Its azerite traits directly increase the dmg of the spells you use in pvp. Add in arcane power on a 1.5min cd and you can burn people down very fast.