There's a big thing you're missing. Between 2003 and 2010 what % of the FFXI player base owned a Relic Weapon. (even just 1)
Relics have been in 14 for what, 8 months what % of the XIV player base owns them. (and in many cases several)
Until Abyssea relics were so damn rare that it wasn't an issue. According to the 9th vana'diel census (the one before Abyssea there were 3,246 completed relics (of any type) across all worlds.
(Click here for source)
There were what 30 servers around back then so about 100 relic weapons per server.
The relic of XI was a whole different calibur to the relic we have in XIV. In XIV the current relics are Incredibly common place for something that's supposed to be a Relic. If I recall though Yoshi had said what we currently consider relic won't always be the best weapons, something considered relic now might not be relic at somepoint in the future. If you follow the PLD story there were 4 mighty swords forged or something. Maybe at somepoint there'll be a totally new "relic" quest for one of the other 3 swords and curtana may become obselete as a relic weapon.