1) _This isn't just a matter of taste._ Choice of license has moral value. Although legally "it's my party and I can GPL if I want to" I don't think this is the case morally, and I try to argue that it the post.
2) _Copyleft is not anti-copyright._ Copyleft imposes additional restrictions that are not possible in a world without copyright. Copyfree (and specifically copyright waivers in countries that allow them) best simulate a world where we can share freely and also choose to withhold freely.
3) _Copyleft is often used specifically to sell proprietary software._ This is because the arrangement between creator and licensees is much more asymmetric in copyleft. If you're directly selling the software you're licensing then you're probably going to need to use a copyleft license.
I think #2 is well known although not often written about, and #1 seems contrary to what people on all sides (copy{right,left,free}) say. I haven't seen #3 written about elsewhere.
Those are my points, did that clarify or muddy?