The Turing Test is a good test because we know it's an extremely hard problem. That all it represents -- an extremely hard problem.
Even when people were first building programs that could solve chess, it was well understood that it was going to be a lot easier to solve chess than to solve the Turing Test.
Whether passing the Turing Test indicates anything about Artificial Intelligence is just a matter of definition, to be sure. But the reason that it's considered a fairly good measure is that it's hard to see how any program could beat the Turing Test without "human-like" intelligence.
Sure, you could hard-code in more and more and more responses, like these guys who code these chatbots do, but most researchers are quite convinced that such an approach will never fool a human for very long. A real conversation is just too complicated. In order to have a real conversation, you have to do something that's several orders of magnitude more complicated than what these guys are doing.
Now, you're right that if, in fifty years, someone were to be able to write a bot that's 50-trillion hard-coded sentences, and can trick someone for several hours, we'll say "that's still not Artificial Intelligence." But as far as we know now, such a feat won't be possible.