My opinion didn't match any of the poll,but my opinion may be similar to VEL's.
1.For example, they could be obtained in mini-events where players play at a certain difficulty level for a short period of time, like the one-week 5th anniversary of TTFD.
2.Alternatively, they can be obtained as rewards for completing end-game content that will be implemented in the future.
This has nothing to do with the topic, but as long as there are items that are nearly impossible to obtain (like custom weapons, or items that only alpha/beta testers have,etc...), there will always be people who say it's unfair.