No, you definitely don't need walk mode for resort-only riding. Standard boots without the walk/hike mechanism are actually the better choice for most riders who stick to lift-accessed terrain. They're lighter, simpler in construction, and typically less expensive than their touring-equipped counterparts.
Walk mode adds a mechanical switch and moving parts, which means more weight on your feet all day and a potential failure point over time. For resort riding, that's an unnecessary tradeoff—you're strapping in at the top and riding down, not hiking for miles. The stiffer, locked-in feel of a standard boot also delivers more consistent power transfer to your board.
The one small perk of walk mode at a resort is the easier stroll from the parking lot, but that's not worth the added cost and bulk. Save walk mode boots for splitboarding and backcountry missions, and go with a standard boot if your feet stay on the groomers.