The need for theme park reservations is determined by the type of ticket you have, not whether or not you are staying on-site. An AP or other non-date-based ticket will need theme park reservations regardless of whether one is booked cash (regular hotel booking) or
DVC or staying offsite.
Other perks of onsite -- early entry, deluxe extended evenings, free theme park parking -- are the same for anyone staying at a WDW resort whether booked as cash or DVC.