Semi-agreed. Reddit is minimal in that it is pretty simple and straightforward to use. Not minimal in the designed-to-be minimalist sense.
The best example of this is Google and Apple. Both are minimalist. But Apple (arguably, of course) has a much better sense of design. Reddit is like Google.
I'm not in the Apple boat, but I do know what you mean about the Google-iness of Reddit, and more generally the Google-iness of Google. Aside from google.com itself, there's something about everything they design that is very off-putting in a way that's hard to describe.
To my eye anyway it always looks like Google got the developers to do the design as well (even though that's probably not the case), whereas Apples' designs have a little bit more of an "artistic" feel to them
If you think about the elevator pitch or even the 5-10 seconds of someone's attention you may get, "the X of Y" is a pretty efficient means of communicating what you do and how you do it.
Sure it can also get overused and there is always the trap of thinking that there has to be an X for every Y ("the Priceline of Dating anyone?").
Though the design may be minimalist (though arguably, hipmunk is just well designed, minimalist or not), I seriously doubt that is their formula.
The success and buzz around hipmunk is that they have provided a better way to search for flights. That they've done it with a cute logo and minimalist design is maybe a small part of the success, but their ability to create buzz and to create great products can't be overlooked.