When I did my PADI AOW, the e-learning made a big point about depths. So first, I want to reiterate that there are no diving police and that you don't get "certified to" a certain depth. As an OW diver, you can certainly dive below 60 feet, but you will likely find that certain dive shops/boats won't let you dive deeper with them without AOW (or a deep diver cert). I'm not telling you to exceed your limits, but slowly becoming accustomed to diving below 60 ft is a natural progression. Anyway, what PADI talks about in the AOW course is that the recreational diving "limit" is 130 feet, but they recommend that divers stay above 100 ft. to avoid narcosis. Now, of course you can get narc'd above 100 ft, but the chances are reduced.
Also, what you really need to be careful about when diving deep are your NDLs and air consumption. Once you get below 100 and certainly when you get near the 130 ft mark, your air is going to go a lot faster....at least for most people. Also, your NDL will be a lot shorter. These are things you'll be taught to manage in the deep diver course (IIRC), but also in the AOW to some extent. I do recommend AOW because you have the opportunity to get a taste of a variety of available options for specialties if you want to also go that direction. However, if you really want to do a lot of deep diving, then you might want to look into the deep diver certificate instead or in addition to AOW. I like having the AOW certificate because there's never a question about depths once the shop sees that card.