Singapore is a very realistic country. It offers you money, on the hope that you can contribute in the future, in one way or another.
Ther reason why most of the scholarship are for computing, science, engineering is that unlike other courses like law, architecture etc, engineering etc are extremely flexible in the sense that in the future, an engineering graduate can easily take up any other course as they wish in their career stage, like management, marketing, business.....
Well, as you are young, it is good to have dreams and passion... but on the other hand, do make your choice as wide as possible so that in future, you can be fast to adapt to the change and equip yourself to challenge and strive for the best.