Things Wyll deserves:
1. More reactivity from companions (they say nothing when it's revealed that Ulder is his father, for example)
2. Dialogue option where the player can choose to not be a jerk to him (see the "be nice to Wyll" mod on nexus for elaboration)
3. Literally any emotional catharsis in act 3 (be it in relation to his dad, Mizora, etc.)
4. A Mizora boss battle (She could have been a legit threat to Ulder's life in the Iron Throne fight, but nope, she threw spiders at him and called it a day. womp womp.)
5. An actual romance scene in act 1.