Ah, a good topic there.
SQEX doesn't do anything to point out mistakes or if you misunderstand the game.

One thing I'd like that goes into your 1 is a Death Recap. It's a shame to admit but we struggled in our E9S prog because we couldn't exactly figure the beam mechanics right away. Am I dead from a share, did I died from something I should avoid? Usually they tend to point avoidable damage with insta-death or vulnerability debuff.
Other times, there can be debate when a tank dies, is it the healer or the tank fault? Damages shown on death recap would be usefull aswell.

Another tool I'd love is something like XIVAnalysis, a tool that doesn't look into your DPS, but rather into your rotation.
Did you break a combo? That goes into a report.
Did you overcapped resources? That also shows how much and when you waste resources.
Your big cooldowns are in the raid buff window?
Did you correctly used mitigation?
Did you left a GCD drift and missed uses?

And on and on, ways to improve your performances and only available to the player. And why not getting a score for savages/ultimate you could show in your profile so your abilities could be gauged.