Canucklehead,
(and I LOVE that name!) For some people that AI is the way to go. For expample, if you have teenagers that can eat their weight in food every hour, an AI would be a good idea. For people that don't want to "wander" then an AI can be like a grounded cruise ship. If that is what you are looking for, then that is super!
However, let me just point out that if you read the reviews from people coming back from Cozumel, there are two major recurring themes in almost every report: 1) the great dives and 2) the restaurants. If you read a lot of the reports you will see that most of the people that pay for AI still end up going out for at least some meals. That certainly tells me something.
I read a lot of the Cozumel reports as I am always trying to learn how to improve on my experiences on my next visit. I don't see many people slamming the food at AI's, but the recurring comments seem to suggest that the food tends to be mediocre at best at most AI's, and the selection is pretty limited. For some people that is unacceptable, for others, they don't care. Again, it all depends upon what is the "big knob" for you and yours.
Southern? Northern? Depends upon what you are looking for in your Cozumel vacation experience. Some people want to hang out in luxury, some people value the island experience more. Personally I think it would be a shame to go to Cozumel and not get a true feel for some of the island culture and charm, but that's just me. I stay in a small hotel in town, and I walk every where. My buddy didn't like the walking so much. I like to explore some of the local eateries (especially for lunch) where you get authentic and economical food. He prefers the more tourist oriented restaurants and (shudder!) MacDonald's. Yes, he insisted that we go there one night. (I did not eat.)
I just have a natural aversion to paying for taxis when I can stay close enough to walk to things. Of course, to each his own.
The charging for use of the private pier is definitely a hot button for many people. I can see both sides of the issue. They paid for the pier, and they want you to give your diving dollars to their dive operation. You paid to stay at their hotel, and you want the freedom to dive with whoever you choose to. My American business sense would tell me that they should figure out what their dive operation is not providing so that people would not choose to use other dive operations, but it is not in America, so things are a little different.
One of the beauties of Cozumel is that there are hotels and dive ops and restaurants etc for everyone's budget and priorities. Each just needs to find ones that match up well with their "needs". Regardless of where you stay or how much (or little) you pay or what you eat or whether you walk or take a $40 taxi ride, we all get to dive some fabulous dive sites!
Variety is great, and I can find space at restaurants and on dive boats because other people like other choices!
Look how many people go back to Cozumel year after year after year. That certainly tell me something!
Just my random opinions,
Wristshot