It may be easy, but it'll still take time to develop. If it's not critical and won't keep you from getting your initial batch of users, it's much better to launch and add it in 3 weeks, rather than waiting an extra 3 weeks to launch.
I may have sounded a bit negative, but I don't think it was a "bad" move, especially seeing as how I am personally excited about Grid even without it currently having this feature.
It just shouldn't come as a surprise when a lot of people question the choice of leaving out the #1 feature of spreadsheets. Even on version one.
