From my (limited, I Am Not A Lawyer, etc.) understanding:
First, it's expensive - you should count a good S$5k SGD/year if you go through an established player (e.g. Hawksford, who you are quoting), maybe a bit less otherwise. This ad infinitum, as you need a local director to keep the company open. And unlike in Hong Kong not so long ago, it has to be a real director - someone who theoretically can open bank accounts and hire people - so you're taking that risk too (the director will, conversely, be taking the risk that you might be a scammer or other criminal whose acts he'll have to answer for in court).
Then you have to put in S$50k in capital in order to be able to apply for a visa (EP) for yourself, should you want permission to work in Singapore (if not, you'll get taxed at home when repatriating profits); this visa will require, today, at least S$4-5k/month in "salary" (which will be taxed).
This also assumes that the Ministry of Manpower doesn't suddenly catch upon this very convenient way of getting yourself what is effectively an investor visa at a fraction of the investor visa cost (which they did two years ago with the EntrePass, which is today utterly useless for most foreign founders due to its requirement to have funding from a short list of approved VCs). Guessing what MoM wants and is going to do seems to be a bit of Kremlinology which HR directors love talking about as their special value add, but it is a bit opaque and the rules change with time, elections and special circumstances (like the famed riots last year, or the Ferrari and taxi incident).
The "plan" should you want to take advantage of Singapore's otherwise fantastic conditions for running a business is to get PR, which takes up to 3 years employed locally (depending on salary - someone on a high salary and from a "desirable" country might get it in 6 months). Singapore is fantastic... for local founders. Or if you're willing to pay.
The days where you could be in business for USD 1,500 and a flight to Hong Kong appear to be, unfortunately, over. I'd love to be proven wrong...