Obviously, a bus on New Bern worked for the 43,000 people who rode it in September, and a faster bus will probably work better.
Also pertinent here: transit is about shaping the future, not the present.
People make choices based on the modes available to them at the time. People will make different choices once BRT is available. The biggest choices are when people choose new office, retail, and residential locations – especially for businesses.
Right now, downtown Raleigh isn’t really the most accessible location in the region; it’s not faster or easier for the largest number of people. Bulldozing much of downtown for highways and parking lots will (a) never succeed in making downtown more accessible, given that the suburbs will always have more roads & are closer to suburbanites anyways; (b) will destroy most of what makes downtown special anyways. So downtown has to compete with transit.