Whether or not it helps residuals, it will certainly help you sell the car. A few year's ago I was looking at a Macan Turbo outside a Landrover dealer. A salesman came across and I immediately said I wasn't interested as it didn't have a sunroof. He said everyone had been saying that, and that they were struggling to sell it.
I'd always recommend speccing it. Primarily because it's a very nice thing to have. Secondly it will help you sell the car as the next person will likely want it.