I find it weird for existing Premium bus services to terminate
at Fullerton Rd. Why not SBST extend to Suntec City? I believe may
help to increase ridership. Anyway its just another short distance
away and SBST will stand to gain. 
Ridership sure increase but then the premium bus service rules
states that no standing is allowed. To add on, only a single trip
per day and some buses uses single deck.
Like you said, it's only a short distance so I think fellow
office workers would maybe walk down to Suntec city from Fullerton
Rd.