Nobody would ever see it. Enabling new feature discovery in software is a very hard problem. Just throwing in features and hoping people will find them is not a good philosophy.
In this case, I would probably have shown it by default with text including "why am I seeing this?" and a "don't show this anymore" button.
I provided a customize button beside the amazon search result page for users to disable it. But it seems many users don't like it, so I removed this feature completely.
1. The feature is orthogonal to the plugin. Alone, you probably could have survived this one.
2. The feature came to light for many through negative press. With number 1, that pretty much kills the feature in the current extension.
Rather than just killing the feature altogether, though, you could release it as a new extension. Add a couple other ecommerce sites and call it a shopping assistant.
In this case, I would probably have shown it by default with text including "why am I seeing this?" and a "don't show this anymore" button.