Not trying to pick a fight here, but come on - really?
Your advice is sound at the beginning -- endeavor to not run aground in the first place. I think we can all agree that that's the best course of action. After that it gets a little preachy and holier than thou. Perhaps you are blessed with sailing grounds that don't include skinny water, and if so then my hat's off to you.
Your advice of "If you are tempted to enter waters of which you lack a confident picture for any reason, and you are concerned about grounding, go someplace else" would pretty well take much of the AICW off of the table for recreational sailors.
There's a huge difference between a multi-million dollar ocean going ship and your average recreational sailboat. First off, there's very little reason for these ocean going vessels to venture into relatively shallow waters that are not clearly marked shipping channels. Secondly, even a gentle grounding in one of those puppies is going to cost huge bucks to undo in terms of both floating them off and in returning them to full commission.
Recreational vessels OTOH spend most of their time outside of marked channels, often (at least here on the eastern half of the US) within a few vertical feet of the bottom. Every once in a while that narrow buffer disappears entirely, even with the best of intentions and attentiveness. The OP's question was "what next?"
Well, I've cruised in 3 different boats for 30 years from Canada south to NYC and have touched once (touch wood) in all those years, while seeing many, many beautiful harbors. But I have avoided sticking my bow where it shouldn't go. I most certainly have spent time in "skinny" water with a few feet between my keel and the bottom. But that's just the point you see. Make certain that you do indeed have a few feet of margin, or go elsewhere. That simple.