While I agree that more options need to be exposed to make things more easily tunable - you need to bear in mind that the engine has to scale to a wide variety of projects.
It is unreasonable IMO to expect the default implementation of TAA to be perfectly tuned to your use-case. It’s also widely accepted now that people have to expect to dig in and make their own changes to better suit their needs. Most other engines don’t let you do that - and if you can’t do it yourself, you can almost certainly find someone who can.
Probably worth stating that a certain other popular engine also only has FXAA and TAA by default, and it’s TAA is nowhere near as good as Unreals IMO.
There are also third-party solutions you can consider implementing:
NVidia’s TXAA
Community Members SMAA
You can also super-sample natively, but obviously this is expensive and should be an option left up to the end user.
I suggest reading through this. It’s old but still relevant.
There’s also an age-old community thread here of people who have played with some simpler tuning values:
https://forums.unrealengine.com/deve…AA=&viewfull=1
…really?