It sounds like you havent done the math. Gunnery 4 with CLPL at ranges 7-8 is a base 4 to hit before other factors (Pulse cancels out Med range). CLERLL at that range with Gunnery 4 is also a base 4 to hit before other factors. Exact same numbers. Will also be same numbers for both pilots (6 to hit) at range 15.
That proves that it is I actually did math about this. You should continue the calculations and end the formula, rather than stop at the middle of the line and says that it's done.
For a gunnery 4+ pilot, with long range bracket penalty of +4 the pilot should have a 8+ to hit, sure. If that is nothing but target practice. The movement of both the attacker and the target is what you should consider. Even if the said pilot only use walk/cruise move, the difficulty is increased to 9+. That means, to hit modifier by the movement is +3 it means it's 12+, and +4 or more means the pilot is not able to hit the target at all. It is not something you rarely see, for +3 is only acquired by running/flanking move of 7+ or jump/airborne movement of 5+, that is even the heavy mechs/vehicles are able to reach without much problem - not to mention that even a 100 tonner mech can do this too, for they can use improved jump jet. And it's before think about the other factors such as cover, the attacker makes run or even jump. Even on the plain ground without any cover, that's the actual result of aiming against long range bracket.
Also you have an error on your math - while you did said 'cancels out' the pulse bonus on medium range, you did not puts the same penalty for the medium range either. Actually, only on 15 hexes it is true that those are all the same, sure, for it's the long range of CLPL and is the end of the medium range of CERLL. But that's only true at just 15 hex. On 16~20, CLPL have same difficulty to hit while CERLL suffers +2 to the difficulty, and on 14 or less hex, it's the medium range of CLPL. On 21+, either sides are unlikely to hit the adversary anyways, due to either out of range or have too much TMM to actually score a hit.
If two weapons are have the same chance to hit on a specific one point of range but on the other ranges one is always inferior to the other, then I don't think that 'one' have any advantage over 'the other'.
Had a tournament once where opponent parked his Rifleman IIC on a hill behind cover. And I knew he would make a beeline for that spot.
So I parked my entire force at 24 hexes which added up to be 6 CERLL's & some clusters which had 8 & 9's to hit first round and 7's and 8's following round. Did a stack of torso damage I took off one of his arms, and reduced his firepower to half (blew one of his arms off) before he was able to eventually return fire from abandoning his sniper spot (took 2 rounds to move 4 hexes as there was a sloping hill the other side).
I tend not to point out tactical advantages without having tried them in actual combat.
How it is possible to only need mere 8+ to 9+ to hit with those? Didn't either sides have moved their units?