But I have to ask an honest question: do you have a deficiency for which
  you need treatment? Or do you have a personality type which might make 
  you unsuited for certain types of work? Or -- more likely -- do you have 
  a tendency for a type of personality attribute expression which varies 
  depending on various external stimuli?

  I think it's perfectly fine that something like ADHD is a naturally-
  occurring personality trait and/or state of mind for which we might need 
  medication to overcome. At the same time, I'm not too happy with 
  characterizing it as a disease or dysfunction. I think we are taking 
  people who are acting in a completely normal fashion and telling them 
  something is broken about them. That ain't right.

I love the way you put this, and I agree with a lot of what you said. BUT I also don't think what you say is incompatible with treating focus issues as a problem that can be helped by medication.

For me, learning about ADHD was very liberating!

It wasn't a diagnosis that told me I was fundamentally broken as a person; it was exactly the opposite.

I had a lot of love and support growing up in the 80s and early 90s, don't get me wrong. But I also got a lot of negative reinforcement and had come to think of myself (as a certain book title suggests) as "lazy, stupid, or crazy" (ok - maybe just lazy or crazy) when it came to focus and procrastination issues. I never even considered ADD/ADHD because as far as I knew, it was a label for hyperactive kids and I was never hyperactive.

Those are very broad terms, you know? I really felt like there was fundamental shit wrong with me. I grew up believing in hard work but had the hardest time doing homework and taxes and things I didn't want to do.

So learning about and eventually being diagnosed with ADHD really helped the way I feel about myself. Instead of feeling broken on some fundamental level, I came to feel like I had a pretty specific thing to deal with; one that could be helped by medication and proper sleep/diet/environment/exercise.

Edit: I also want to address this one specific thing you said:

  Or do you have a personality type which might make you unsuited 
  for certain types of work?

I can't think of a single line of work that doesn't benefit from an increased ability to focus.

Even entrepreneurs, who are often famously ADHD (or ADHD-like, anyway) in their restlessness and curiosity, need to focus on the mundane stuff sometimes.

And it's not like medication erases those positive ADHD traits either. The fact is that stimulants leave your body pretty quickly, and with something like your Adderall dosage from day to day. If you're responsible and take a little bit less on the days you don't need it, you can take a little more on the days when you need it more. You can tailor the effects a bit depending on your needs on a particular day.

(Note: The medication is far from perfect; it's not for everybody and is not a cure-all. Biologically, stimulants are a very crude way to address one's focus. In my experience, proper sleep/diet/exercise/environment are more important than any medication I've tried.)