People click more often on "like" than on "share", it’s a known fact. It’s just one click. Share, on the other hand, it’s more complicated. You have to choose a thumbnail, write a short description… way too much work.

On traffic terms, share beats like‘s ass. On various test conducted on my other blog, liking a link gets only 10% of the traffic a shared link gets. Same thumbnail, same short mindless description (ok, i cheated, it was the same photo, i liked the link first and then i shared it on my wall).

So, an optimisation for share is important.