The datamined 4* leaks are not the issue, I doubt most people even know about them.
Since then, 4* Ayra stats have been taken down and 4* Arden stats have been put up.
That's bizarre. First time I've heard of it since I've only seen speculation that IS would actually remove Ayra's 4* data after putting it in the game but there hasn't been an update yet so it looks like this is just the dataminers screwing up. I wonder where those stats came from then, maybe the 4* Ayra stats were for the story missions.
Also, the issue is that this is the first time a new unit has been released without being featured in a banner teaser video. The way she was cameo'd in the banner video matches up with how previous TT and GHB units were teased, so there's the issue of broken expectations.
And more importantly, she was released on a banner with old characters while sharing a color to boot which is really really bad for people with limited orb income since your chances of getting a single new unit goes way down. It sets a very bad precedent - what if they introduce Micaiah on a banner with Oboro (for some reason)?
I confess I fell for the bait and now I have Lachesis, Eldigan, another Lyn, and Saber. I'm somewhat salty.