I don't think they should remove the "throw" or "melee-ranged" abilities but instead upgrade them.

They should not interrupt combo, that's already what makes them impractical.
In my opinion, they should be a combo, a 2 GCD combo filling gauge/resetting buff duration like current AoE combo actually do.

The tricky part would be to balance these abilities to make sure they're not a big loss, but strong enough to cover the moments where melees needs to take more risks than casters/ranged to just hit the boss.
It could be like the GNB's second combo, the first GCD is on an independant cooldown. Even with the current "Throw" not breaking combos, I doubt they would be used more than once every 30s.

I see two scenarios:
-Cooldown based GCD with a follow-up/special effect (Ex: Increase by XX potency your next melee GCD)
-Ranged Combo with gauge/self-buff refresh effect.

In any cases, ranged abilities for melees should not interrupt their combos.