Canonical TFT assigns XPs to individual characters based on what they achieve. Assuming that we want:
- All characters who are similarly engaged to progress at similar rates
- Characters to be viable in a range of roles (melee, archer, wizard, scout, skill monkey, etc.)
Then we need each kind of character to generate XPs at a similar rate.
By category:
- Fighters are OK, they generate XP by hurting people. Wizards are much the same with a bonus for casting spells in combat.
- The scouts are relying on a reasonable number of IQ rolls to spot things. The thieves are relying on a reasonable number of rolls to remove traps and whatever. Both these character types are heavily dependent on the awards for rolls that Steve is considering deleting.
- The skill monkeys with tactics, physicker, etc. are in trouble because they don't get XP awards for that role, and they won't be as good at fighting as the specialists.
I would be perfectly happy just awarding points per session or objective or whatever. But if Steve is retaining the current system then he needs to keep the awards for non-combat activities, for the sake of non-combat characters.
As for passing the roll being reward enough, the same argument applies to victory in combat.