The guidelines say:

  Please don't do things to make titles stand out, like 
  using uppercase or exclamation points

and:

  Otherwise please use the original title, unless it is 
  misleading or linkbait.

I think the idea behind this change in title is because the original is perceived as being linkbait; it has an explanation point, is very opinionated. The kind of thing that really tempts you to click through, or come and post a scathing rebuttal, because of how strongly worded it is.

Not saying I necessarily agree with the new title, but it is milder, and I think that in general moving away from clickbait titles is a good thing. There's enough clickbait junk going around the rest of the internet, having at least some standards at HN is fine.