2. (and many would disagree with me on this) You are comfortable with the flash on the hotshoe, in
eTTL, and
bouncing. If you've been reading the Strobist, you may be tempted to think that on-camera, eTTL, and bouncing are completely useless and not worth learning. They're not. Hobby assumed, when he started the blog in 2006, that the only people he was blogging for were fellow photojournalists who were already very conversant with bounced flash and wanted to get past the limitations of the same
for editorial work. If you are unaware of what on-camera bounced flash can do, go read
Neil van Nierkerk's Tangents. It is to on-camera flash photography what the Strobist is to off-camera flash. Chasing kids, event shooting--these are completely appropriate times to be using on-camera bouncing. It's smaller, lighter, and much more convenient than going Strobist.
Going Strobist means adding a lighting bag to the gear you already cart around. There may be times you still want to use flash without all the extra gear.
For me, it was simpler and easier to learn off-camera flash by starting with a single on-camera flash. YMMV.