There's this of my popular scriptural saying about being grateful to God, it goes thus; "thank God for what He has done, for greater He will do". Appreciation is a key role in encouraging people to do more, giving thanks to God gives Him more reason to bless us the more. This is applicable to every human also, appreciating them when they assist us or help us in a way encourages them to wanting to do more. So being grateful to God is very important and sacrosanct.
RE: Gratitude - A trait for true Christians. (Luke 17:11-19)