A job having the highest personal/raw DPS is just a matter of tuning. Had they given WHM's attacks 10 more direct and periodic (where applicable) potency, that equation would be flipped.
Which sounds like the kind of job that would provide insights into the enemy's defenses, allowing further damage against them, or likely to buff attacks in general? The elementalist, or the job whose core actions translate to the likes of "Encouragement/Affirmation" and "Assistance/Boost Morale", from the Latin or Japanese.
If the problem is too little damage, the solution is just... more damage; the type of that damage is irrelevant except in that some fit with the theme as given better than others. There's no need to stray from identity just to insert a new type of damage production as if that type were a necessity.
And for my part, I'd have much sooner taken more ability to fill gaps and make exploitations of my own as WHM than a damage buff. That immediate pressure, and the that greater swing between healing and attack GCDs, is what made WHM feel like WHM to me. I wouldn't want to siphon that off towards a raid buff.
For my part, I don't mind having buffs actually worth playing around, and prefer having that something to play around over having nothing. Short of replacing LB with a job-specific variant of a raidbuff, though, so just one gets used but at least 1 is always available, though... our chance of having that layer of gameplay relies on the presence of buffs across enough of our jobs, so I don't mind, for instance, that DRG has Battle Litany, even if it doesn't seem super tied in with the job's theme. (It feels Ishgardian/Halonite [and vaguely like the Karoliners around the time of the Swedish empire], which is fine, I guess[?], but that also feels more Lancer-ish than Dragoon-ish.)
For that reason, though, I'd gladly see Searing Light removed (its rDPS obviously replaced) and would be fine with Arcane Circle made a self-buff only, since neither is generally worth holding anything less than a 90s CD even a single GCD for.