Let's not "looks at fucking CoD", like ever. Make a Halo game.
Also DMR is a reskinned Halo CE Pistol without the core mechanics of skill based aiming and movement to support it. I love single shot precision weapons, they are great for Halo, as long as the core mechanics support it. I'm pretty drunk as well, but the BR outcry is nonsense, BR is only viable because of how stupid easy it is to aim in Halo past Halo CE. Single shot, precision rifle is a great utility starter weapon for Halo as long as it takes skill to move and shoot in Halo again.
DMR was overpowered in Halo 4 for the same reason the Pistol was overpowered in Halo:CE. It was viable across every range, which allowed it to dominate.
DMR in Reach, while problematic, wasn't as overpowered, because bloom ensured that you had to reduce your rate of fire at range to maintain accuracy, and increasing your firing-rate in close-combat also hurt accuracy. So you had a utility weapon that dominated at the range most of the battles in Halo start at (mid-range), and then got noticeably less useful outside that intended range.
The BR in Halo 3 was relatively well-balanced for the same reason. In Halo 2, it was overpowered (though not nearly as much so as the Pistol in Halo:CE) because of hit-scan. In Halo 3, the spread of the bullets insured the weapon gradually decreased in effectiveness the further away your target was. You could always be sure the first of the 3-shot burst would hit, which meant that you could ping snipers out of zoom, but the remaining shots might not, ensuring that it didn't dominate at range quite like it did at mid-range or in close.
A balanced DMR would have a lower range and a lower rate of fire. The lower range and lower rate of fire would still allow you to defend yourself at range, but just enough to maneuver into effective range for the proper battle, or to get yourself to cover, retreat, reacquire, re-engage. The lower firing cap, would ensure that in close, up against AR, or pistols, or shotgun, you would likely come out on the losing end - forcing the player to play smart instead of just charge in with their go-to gun and hammer the trigger.
I agree with some here who suggest that the BR should be a pick-up on the map. A more short-to-mid range option, that allows you to deal damage faster in close, but loses some effectiveness at mid-range, and loses a great deal of the ability to combat snipers or defend oneself at long range. If a DMR and BR meet head to head, the DMR user should be trying to create space, while the BR user tries to close. A battle of tactics as much as one of aiming.
TL;DR version
3 Necessities of a balanced utility weapon:
1) Strong at mid-range, where most battles in Halo initiate
2) Useful for defense at long-range, able to knock snipers out of zoom or pester players (range cap and/or fire rate cap can achieve this).
3) Should have a disadvantage at close-range to close-range specialty weapons (fire rate cap can achieve this)