Are bags worth more than what you can store in them?

I picked up the Guardian pack and that means I have the fastest mount as well as a top level companion for all my characters. The only convenience items I'm really missing is bags.

Here's the thing though, I could blow a ton of my astral diamonds getting a bag for one of my characters (I take it they're character bound?) but it seems like in that characters entire life I'd be better off just not picking stuff up once the bags were full, unless those items were blue or I was specifically looking for them.

Is that about right? Items are pretty worthless unless you can identify them, and my intuition says you get more items than identify scrolls anyway (otherwise what's the point?) If I just leave that trash on the ground I can avoid both issues.

On a related note does anyone know just how much rarer identify scrolls are than the relative items? I've been avoiding identifying stuff since I figured it's better to save them to the higher end (if I use an identify scroll on a level 4 item I'm losing a ton of money compared to using it on a level 29 item)