They even covered that a bit with Rachel.
1. She fought Necrom and died, was resurrected by the Phoenix that same day.
2. She went into the future 2000 years and fought against the Acolytes of Apocalypse, she died in her first battle and resurrected immediately. After that Rachel started taking massive risks as Askani and died at least six times before finally pushing the Phoenix force into Diamanda Nero as the only way to defeat Diamanda. Technically after that Rachel only had a small echo of the Phoenix force and she stopped being so reckless and started being more careful. However, after she died of natural causes in the Askani timeline Rachel resurrected again in the timestream where she reappeared at Gaunt's prison at the end of time where Cable ended up having to rescue her.
3. In current X-Force the Askani timeline still exists, so that means that when Rachel died as mother Askani, the Phoenix force resurrected her again and restored her to the timestream.
So yeah, I don't begrudge Jean getting a shot at multiple times to come back. It seems to me that Rachel and Jean both bore the Phoenix force longer than anyone else and they both probably have an echo of that power in them, so it's not unexpected that they they would keep coming back since the whole point of the Phoenix is to rise from the ashes of your death and resurrect. Life > Death > Rebirth in an endless cycle.
I would kind of like the comics to explore a bit more about the repercussions of being a long term Phoenix host, are Jean and Rachel immortal now, will they always resurrect even when they aren't even hosts anymore. Is there always a part of the Phoenix force permanently bonded to both of them. Rachel/Phoenix once told the members of Excalibur, Jean, and Charles that "Now and Forever I am Phoenix!" So my question is if you are resurrected even one time by the Phoenix does that mean you are permanently tied to it's power for good. Young Jeen appeared to be destroyed by the Phoenix at the same point that it resurrected older Jean, but then Jeen returned again from the White Hot Room. So after doing that one time as a teenager, was it almost pre-ordained when she went back in time that inevitably she would become a Phoenix host because she was already primed for it because of her experience while transported into the future.
Haha, I love trying to make sense of X-Men time travel, it messes with your mind.