I can understand that the game needs to end, but at least there should be some options:

Add a different ending where the battle between the Legion and NCR isn't decided and everything remains as it is.
Some kind of optional stalemate ending for those who want an "open end".
But I don't know if this would make sense as it's pretty much the same as not activate the Hoover Dam battle.

Or give the players the opportunity to start all over again with their old char (some kind of "New Game+") and they
get a reward for doing so: be it additional points for stats or skills, maybe a free or special perk, special item, something like that. But the difficulty level should also be increased when doing so.

yes i agree but it cant look exactly like it if its coming from a dlc it would have to be old and battle hardened from an older legate, or similar armor just from a different faction, heck maybe the mormons leader has it except it's silver and blue instead of gold and red with some crosses on it....i feel like i got off subject

If it becomes available in a DLC then it better be a Legion faction armor.
What?
You think you stroll through McCarran as the legate without being shot?

well if its war torn and you dont have the helmet, i dont know if i could tell...other than the cape, but it could be partially singed or even gone