No, all it means is that there is an occasional exception which is not unexpected given the number of skills. It could be a mistake or oversight in the Drill Cannon tooltip. A single counterpoint does not completely invalidate anything. There are other exceptions out there. E.g. Dragoon's jumping attack lists that it is a fire jumping attack which is ambiguous to whether it does physical (attack) or elemental (fire) damage.
It doesn't sound clunky because it says exactly what it does just like every other magic damage dealing ability in the game. They all use the notation: "deals <element> damage." Where element is fire, lightning, ice, etc. and if there is no element then it is unaspected. It's not hard. Adding the word attack adds in ambiguity where there is none which is counter to your entire request, especially when RDM has a buff that is specific to that difference. You can see this just in the RDM weapon skills themselves. Unenchanted ones use the word attack and the enchanted ones use unaspected damage.
Looking at the ranged skills that the melee's have, they either obtain them at level 15 or they are gap closers. The gap closers use the gap closer description which leaves the level 15 attacks. They likely put in the word ranged because of new players. If a RDM can't figure out an attack is ranged from the range attribute on a tooltip by level 76 then that's on them, not the tooltip. Also, RDM kit is primarily not melee so that makes for a poor excuse to add the word ranged to a tooltip that already clearly shows the range like with every single ranged skill in the game. And this is true without exception. Every single skill, ranged, melee, or otherwise, has the explicit range of the skill listed regardless of the text description. Even the melee skills of the primarily ranged classes don't use the word melee in their description. They do indicate something like "cone in front" or "all nearby enemies" but that is a descriptor of the AoE shape which is something that isn't able to be described by the range and radius attributes of the tooltip. Something which a single target ranged skill doesn't need.
Seriously, this skill's tooltip is complete and not hard to comprehend at all and this entire thread boils down to people not properly reading the tooltip and then complaining about it despite that.