Feels like an unnecessary change to address a problem that doesn't exist.
The fact that it's uses on are quite limited is exactly why it should remain a mass spell.
Vision of the Omniscient Eye is not required for any dungeon, in my experience; it's simply a convenience.
Water Breathing, on the other hand, is a literal requirement for...two dungeons? And a convenience for another.
Changing it from a mass spell to a single application adds absolutely nothing to the server experience.
The only change it provides is added difficulty in entry to the dungeon by forcing people to cut down in party size,
and thus pigeonholing people into obeying a specific party range in terms of how many people a party can bring.