He's replying to someone else asking for cars.
And Grant's position isn't necessarily incompatible with the naysayers. Most simmers want cars. The sims team wants to make cars. Even the naysayers would probably like cars if they were well integrated and didn't bring too many bugs or feel too tacked on.
As one of the naysayers, though, I think that it'd be too hard to make cars work right. Lots in this version are a confusing mishmash of private and public spaces. Does Straud's mansion simply count the squares of editable terrain, or does it count the cemetery and driveway areas that anybody could stroll onto from any lot in the neighborhood?
For that matter, how would you drive? In Forgotten Hollow, driving from Straud's mansion to the neighborhood despawn point would require going through road areas that tend to have townies walking around through them. In Windenburg, the island and the area around the ruins don't have roads that a car could conveniently follow. Would the car just poof off the lot, or how would you have it reasonably animated?
These aren't just me being a wet blanket. These are real questions that have to be figured out if you want to make cars something useful and engaging instead of just thrown together.