Eh. functionality over "immersion" anyday. If a character has the skill, and a tool for the crafting class in their inventory or gearset, what is stopping them from "theoretically" whipping it out of their bag and repairing stuff automatically..

If I was a Dragoon in real life, yet I knew how to fix my helmet, I wouldn't get undressed, put on my crafting gear, put my polearm away, pull out the tool, repair it, then put it all back on again, if it just needed a few beats with a hammer.

There has to come a point where "immersion" is sacrificed for functionality. When it simply makes small tasks more annoying to perform, then that is when "immersion" has gone too far IMO.

Global tool - nah. Just an option to repair stuff regardless what job you are on.