Doing my usual whinging. “I love 3.5e, but why can’t it be more like 5e? I love 5e, but why can’t it be more like 3.5e? And there are some good ideas in 4e. And…”
I’m never satisfied by RAW. I’m a collector, not a player, and a syncretist at heart.
My latest gripe was finding out that the Expanded Psionics Handbook (3.5e) ditched the 0-level talents from the Psionics Handbook (3.0e). There were a lot of problems with the PsH, starting with the multiple ability requirements for each type of psionics (fixed in the XPH by making it ability by class, instead… and only allowing psions to specialize in one type of psionics 
). But, dagnabbit, I LIKE 0-level powers for the different classes.
If I had my way, I’d go through the talents in 3.0e, see where they are in 3.5e, and on a case by case basis move them back (adjusting the strength as needed). Then figure out the progression for known and slots.
Anyway, that’s just one of my quibbles and how I would handle it.