Although I haven't been there, but from what I gather, Dubai is good for both business and tourism purposes. Both subjects are inter related depending on how you look at it. I like to think that the core reasons for tourism isn't just about sight seeking, it's also about showing off the entire region, place or country to the visitors. In doing so, it's most likely for tourists to develop other interest, interest like business ventures. Dubai is one of many countries which has been able to recognize this particular advantage of tourism. And that's the main reason why the government spends billions in developing breath taking sites in a bid to draw more people to the country.
From the stand point of business, Dubai is a fast growing economy and eager to compete and make a stand on the world stage, that's if it hasn't already. For this sole reason, the government has made business conditions very favorable to intended starters. Policies and regulations are at the easiest to deal with unlike already developed nations. Asides the ease in government policies, there's also huge demands for goods and proximity to emerging markets. This is what makes business lucrative in Dubai.
Tourism on the other hand is at all time high due to the factors mentioned above and also the country's policies of dominating and expanding it's presence in the world thereby opening it's doors to almost everyone from any part of the world to visit for leisure or business purposes.
Which ever way you look at it, everything Dubai does now that revolves around business and tourism is for the purposeful development of the nation.