In my experience, it's far from a cavalier, unemotional choice for most (not all) of the women I know who've had an abortion -- including myself. Granted, the "when" is the critical factor. Under 12 weeks it is more often viewed as a simple medical procedure; after 12 weeks gives a bit of a pause to more women; after 20 weeks gives much more pause to many more women -- all of whom are pro-choice.
I suppose acknowledging that there is a spectrum of views concerning abortion amongst those who are pro-choice would be wisest. I think it's dishonest of the collective pro-choice movement to frame it as though it's a simple medical procedure that requires no contemplation about one's value system or moral compass or however one wants to refer to it. There are differences of opinion regarding when "life" begins even among those who are pro-choice. While some women may feel an abortion at a certain stage isn't a personal choice they'd make because of their feelings about when life begins, they can still recognize that it is precisely that: a personal choice.
I disagree with injecting any shame, but I also disagree with broad-brush messaging that it isn't a difficult decision for many women. I know the fear is that saying this allows an opening for the anti-abortion people to scream even louder, but I'd rather present the issue honestly -- acknowledging the spectrum of personal feelings and beliefs among those of us who are pro-choice -- than toe the line by dismissing it as a simple medical procedure.
Just my feelings.