I'm enjoying Tinkering, but it does come with one huge drawback. Craft Trap is essentially an EFUSS skill that costs you real skill points. Concentration, Spellcraft and Heal will all benefit any PC who takes them, and Lore is useful for all crafting as well. Craft Trap doesn't do anything but give you an improved Tinkering score.
Thoughts:
- Improve Craft Trap like for Parry and Tumble. For every 5 ranks in it, you gain a bonus. I suggest +1 Open Lock/Set Trap/Disable Trap (maybe also UMD?). You invest 5 points in Craft Trap and get 3 (or 4) points back across other skills. The benefit being that it raises your max skill level in those.
- Make Tinkering work using Set Trap or Disable Trap instead, as those skills have an actual in game use.
I suspect craft trap is used because Tinkering can be done by both Wizards and Rogues, and only Rogues have Set/Disable trap as a class skill.
I think it'd be fine moved to Disable Trap for that reason. Wizards can buff themselves up to higher skill scores and better defence against failures. The downside of not getting your Tinkering skill as a Wizard class skill would also balance out against "I'm a Wizard investing in an an INT-based skill that lets me disable traps, and that's really useful". I took disable a lot on wizards as it was a handy backup skill you could be just about good enough at where it mattered.