Windchill "state" question

It allows your engineers to change a 'released' drawing/model.

Even if you don't do CM through Windchill, you should still have different states for the lifecycle of the parts. When a design is released, the state should be set to 'Release' to prevent further changes to that revision. When a change is needed, the engineer can do a revise to the part and set it to the next revision. Leaving all files at 'In Work' does not protect the system or your data. This also requires your company to set up proper ACLs for data management within Windchill.

Engineers may read or revise a released document, but not modify it.

Engineers may have full control to an In Work document or you may limit them to modify. Full control would give them delete, set state and revise along with other permissions they do not need.

I would say so you can lock down the design, especially at certain mile stones.  Otherwise if someone makes a change and you can never go back and get to the state you wanted the design without a ton of manual work.

It's all too easy if you use states and revisions to add to your workspace the correct revision and/or state of an object.  If everything is at initial revision and in work you might have to sift through hundreds of iterations of a part to find the version you want.