She got reworked because Blizzard didn’t like the playstyle that Rez promtoed. Fun had nothing to do with it.
And how do you only enjoy a hero because of their ult? That’s like 2% of their playtime. The other 99% of the match is just her base kit, which has only gotten better with the GA changes.
If you only played Mercy for mass rez ult, you didn’t enjoy Mercy, you enjoyed rez.