What you describe also holds true for Rogue (Bladedancer/Marksman) and Acolyte (Lich/Necromancer)
This is mainly due to all 3 of them, missing the 3rd mastery, which will most likely create a better overlap between masteries, because all 6 of the current masteries of those 3 classes are on very opposite sides of a spectrum (Spells VS Melee; Melee VS Bow; Spells VS Minions).
For Acolyte it’s the least severe currently, but for Rogue and Mage it is.
I think Mage and Rogue will make a lot more sense with the 3rd mastery and it will tremendously increase build variety with some mix and match builds using multiple different things.