yeah I can see how the behaviour could be confused with broken trackpad.
I personally like it because often links in Mail for instance, is just something i want to check out fast, and not be send to a different app to view, and if its important enough for a longer session inside a browser i can easily make a new tab with it by clicking the button in the preview window.
I know Sigma and Arc have a similar feature, I dont know if its on by default though.
That said i dont have any problems with having it off by default, if its undesired for the majority. only problem with that is discoverability, but maybe thats ok