Some dorfs like work, while some do not, so being free to pursue needs is good for some of them.
If you have a steady migration stream and not much attrition you'll more or less inevitably reach the point where you've got more dorfs than work. You can pick up some slack through military training (some dorfs like that, some hate it).
Given that an excess of dorfs (or other creatures) is bad for the fortress FPS it's probably a good idea to limit the number of dorfs you get via the pop caps (although aiming to become the mountainhome will probably leave you with a lot of idle dorfs).
DF currently does not know how to re-stack bolts, which can cause bolts to become a significant clutter factor. You can melt them down (which results in a material profit due to how DF handles it) and reforge them into new bolts to get stacks. I typically mark them for melting (they're brought by goblins, typically) and that works. Given that used bolts don't stack, you need a lot of space to store them in stockpiles, and it doesn't help that bins are even less compatible with bolts than with anything else.
Dorfs tend not to get rid of worn clothes as they're owned, but cleanowned scattered x typically cause them to be marked for dumped (but you need a dump zone, although a single tile is enough, or there's nowhere to haul them). From there I can get them to be hauled to the trade depot for removal from the map via the garbage trucks, a.k.a. caravans (you need to remove the 'f'orbidden flag to get them moved from the dump zone, but that's easily done with d-b-c).