well actually MSI didnt really do much either. The GT780's came out in 2010, it just stuck to the same chassis under a newer name GT70 and we didn't see any changes until this year (to the new one with the red headlights) when the GT72 came along.
So while Asus has been making minor tweaks (barely noticeable in most cases) to their ROG stealth fighter designs each year, MSI was literally stuck with this for 4 years
But frankly I feel that hardware is more important. If you're like Alienware or Razer now who has still yet to introduce 900-series maxwell into their machines, introducing new designs (like the recent alienware 13 with 860M) probably won't wow most enthusiasts.
