I think it very much depends on how you use HN, if you use it just for the consumption of 'news' then I can see why you would not need search as much, but HN is much more than that.

It's an awesome resource, there are plenty of comments that are literally gems when you're stuck on something or starting with some new tech and that's when search comes in really handy.

For instance, how to start with clojure: http://news.ycombinator.com/item?id=1033503

tell me how you'd ever find that without a search?