Well, you cant have all you want, think about this: Fatebringer was overpowered by the new guns when TDB came out and still a pretty good weapon to use on CE (actually the best primary), if they upgrade it to 331 for HoW then, it will remain the same useful as in CE, also, think just a bit, why would Bungie bother on releasing new guns if the old ones can be actually more powerful than them, that would make new raid guns useless just like the ones of CE, it's just about common sense: people want rewards in new raid, no matter if those are useful or not, and if old guns get upgraded to new max stats the game would loose sense (even more)