gorila glass doesn't really help a phone's brittleness. it is for scratch resistance.
the reason some phones crack easy and some dont is mostly due to the rigidity of the phone. plastic absorbs impacts a lot better than uh glass or metal, so it doesnt transmit shock through to the glass unless you hit it at say a corner where it is more likely to transfer pressure to a single point on the edge of the glass.
its like crumple zones in cars. plastic is a better crumple zone than a sleek aluminum and glass casing like say an iphone (which is idiotically designed for any real durability it seems). when you drop a samsung or htc phone with a removeable battery cover the cover pops off a lot. that is letting the shock energy be released (it is what makes the panel pop off with force)
i haven't taken a physics class in years, bu tthe energy transferred into the phone will either cause crystals to break their lattice or plastic to get a gouge in it, or metal to warp or things to move until its all absorbed