It's part of the whole package for me. I used to be so nervous to carry a handbag as I always felt like besides just being clocked as a man dressed as a woman, I would then be clocked as a dude clocked dressed as a woman and carrying a handbag. Then I finally came to the realization that it truly makes no difference. This was just twisted nonsense that used to bounce around in my head and really held me back. I looked at a handbag as an accessory, which it partly is, and I felt accessories would somehow make me appear even more noticeable in public. I was completely wrong about this though. Now I can't live without a handbag and it's usefulness. I find that I rarely have any stares from folks since I started carrying one. Wow, I had a complex. Now I go for bold handbags and pile so much into them I don't know how I ever survived without one, even as a guy. Forgive me, but I felt like spewing that thought, but I wonder if others have shared those feelings as well.
Now to the original question...Purse or huge girlie bag? I mostly carry a purse or cross-body bag, but when shopping, I carry a large woman's tote. I don't like to carry a bunch of shopping bags, so I can put some purchases in there. Also, sometimes your in a place where the air conditioning is so cold that it's nice to have a place to carry a light sweater with you.
You can certainly complete the look without one, but I find it's easier to carry one.