I find that there is often TATL availability using AA miles, but the flights are on BA metal. That generally means an inferior product and a cash component. The cash component is often about the same as buying a coach ticket. I think, if you want to avoid feeling frustrated and miserable, that is how one needs to look at TATL J redemptions these days - you pay a coach fare, but use the miles to travel in business. Sometimes there will be a better way to achieve the same result. That is basically the same approach many people happily take towards the BA avios scheme.
Of course it isn't as good as it was 10 years ago when AA was losing millions and couldn't fill the premium cabins with paying customers. But, there is still value to be had from AA miles, especially if they have been acquired for free by doing what you would have been doing anyway. Even more so if you have been doing what you would have been doing anyway at someone else's expense.