I wish Adobe would put a bezier pen tool in. There are a few iPad apps that do this well - iDraw and Inkpad are the ones I use the most - and they do a great job. There's a few issues with them both like they create too many points when you use the 'pathfinder' tools and the accuracy of the add points tool can be a bit hit and miss. And of course you are left with a convoluted workflow to get the illustrations into other iPad apps but if you want a bezier pen tool on the go I'd give them a try.
Agree this would be really useful — easily adjusting curves is one of the reasons I prefer drawing in Illustrator to Photoshop. Wish this could also be possible on Illustrator Draw.