Because you cant upgrade the gun fully. The last upgrade you put into the gun, you get from crota, which will make it exotic. Stop bitching about stuff for 3 seconds and think about it. 7 dmg isnt going to make or break the damn gun.

I opened a thread on this before as well. Everyone's reasons seems to be because it upgrades to an exotic, which is the stupidest answer and cop-out response you can formulate...no to mention, so, very shortsighted. I, unlike everyone else, understand where you are getting at. As one who is versed in a multitude of roles and builds, understands that you don't just carry to a raid what you feel like. It is coordinated. Sometimes a group might want you to carry Icebreaker(Exotic) and sometimes they will want you to carry Gjallarhorn(Exotic). When this is the case, you need a good Legendary primary to fall back on. One that suits your shooting style...and the fact that vendor purples are better than this gun, is ridiculous. Especially, given that it takes more work to get. This is the same issue we had with Exotic bounty weapons. In fact, I call this gun the "pre-buff Bad JuJu" as it suffers the exact issue that gun did. As a legendary weapon, I would expect the Eidolon to shoot every bit as good as Doctor Nope, at the very least. Unfortunately, though, it falls short in impact and/ or clip size. Having more of either would help the gun tremendously. Either, they should increase the impact and leave the clip the size the way it is, or increase the clip size. I would prefer the former because the gun is slow at taking down majors and ultras in ways Doctor Nope or Shadow Price do not suffer. Having to reload 3 times just makes it far worse. I was told in a raid, "why are you using that gun? It's doing sh**!" I told them, "it's either I have to use this gun and keep the Gjallarhorn, or I lose the Gjallarhorn and put my Mythoclast back as primary." My point is, the gun is fun to shoot and you have to use it until it is maxed out anyway, so why not make it an effective legendary? Also, not everyone raids. What about those that don't raid? Why can't they have a solid, new purple? Then, of course there's still that exotic special weapon/ heavy weapon issue. You should have the option of using this gun as a solid legendary.

Because Eidolon's Ally is only the second stage. If you know anything about video games, the second stage is never the strongest. I'm guessing Necrochasm will top off at 340ish-350ish. Good enough for the next raid.

At max It's like 1atk stronger than Mytho. And better than Atheon Epilogue. I mean, it's a process. If the weapon levels straight to 331 then the exotic level tree would make no sense missing the 5 damage upgrades.