I think that in all cases, items you can no longer obtain hurts the game in the long run. There will be a sense of FOMO that tires active players while potential newcomers go "I missed my chance for this content, so I'm less interested."
Obviously this happens to different extents. I think far less people are concerned about, say, 1 pre-order minion. But a lot of the PvP items have been very cool, very neat, and very disheartening if you missed them.
I was fortunate enough to already be active when PvP Series were implemented, so I was able to get most (but not all) of the rewards, including several emotes that now make me think "why doesn't everyone have access to this?"
As far as the Series are concerned, I hope they return and become available to all who play PvP. It could be sold for wolf marks, could be sold for trophy crystals, I just hope the option will be there, so nobody has to look at it and say "it's a shame I missed my chance at this."
