I could keep everything in my head--the problem is that I'll forget it at some point, whether it's a week from now, a day from now, or 5 minutes from now. Writing stuff down helps.

You're definitely not alone. But, I've found that even if you don't do it, you should still try.

During my last interview I brought along a notebook, the day before the interview and the bus ride over to the office I wrote down any question that I could think of in the notebook, even forcing myself to think of extra questions.

It got people's attention, I talked with 6 pairs of people and each one pointed it out in one way or another.

Certainly take notes in preparation for an interview. Certainly bring a notebook to an interview. I just don't see this whole "carry a notebook at all times" thing.

Respectfully, what is the benefit to recording your notes and ideas on paper, and using paper at interviews, instead of using txt files in the dropbox folder of the always-connected smartphone in your pocket?

It's sufficiently painful to express myself on the tiny keyboard that I tend to avoid it. Not to mention if you want to sketch something.

It's way more classy to have & take your interview notes on a legal pad or similar. I would bet money if you kept pulling out your smartphone during your interview, you are not getting a job.

A legal pad looks "prepared". A smartphone looks "distracted".