Yeah I can go over Parting Gift now. I will preface this by saying that post-rework, it very very rarely competes with One-Two Punch but to say it’s never worth taking even now is simply wrong.
So before the rework her level 4 consisted of Is That a Health Pack?!, Parting Gift, and Untouchable. Is That a Health Pack?! was and is probably her most niche talent and in my humble opinion has never been able to hold a candle to the other talents it competes with - both post and pre-rework - so we can scratch that one off.
To throw some of those numbers you love to crunch so much right back: IIRC Untouchable only provided more value than Parting Gift if you maintained a minimum of 7 stacks which is simply to unreliable an inconsistent. Also, Tracer has always been about burst damage over AA so why take an AA talent when you can take burst?
Which brings me to Parting Gift. Here’s the real value that you get out of it, and this is true both before and after the rework: You can do more than two melee’s worth of damage (30 more damage at level 0 and almost 100 more damage at level 20) in a fraction of a second. Anyone who’s played enough Tracer can tell you that timing is EVERYTHING. Spending just half of a second too long in the back line can mean your death. With Parting Gift you can dish out immense burst before anyone (outside of the pro scene) has even the smallest chance to react. This is also why I always took Bullet Spray over Ricochet because completely removing the melee animation in place of instant damage is massively valuable (as a side, I more often take the armor reduction talent now because it’s necessary to achieve the 100-0 she had before - and with the tower changes, Ricochet gimps your ability to fight anywhere near towers).
So, while I agree that there are plenty times when the Recall bombs damage is overkill, I can tell you with absolute certainty that I have secured numerous kills over the course of my time playing Tracer with Parting Gift. I’ve even stuck a bomb on one enemy for a kill, then - with melee on cooldown - blinked in front of another low hp target and used the Recall bombs to secure a second kill. It happens very often.