For a longer ride or a trail ride, the loss from the tires adds up. One extra MPH means a lot when you’re doing a multiple hour ride at an average of 10-15MPH.
Tire pressure influences rolling resistance significantly on larger tires. I’ll some times increase pressure on longer rides or for uphill portions. Lower pressures have more traction, so I’ll let air out for the downhills.
It doesn’t seem like much, but everything adds up as you push into longer and higher effort rides. Non bikers roll their eyes when we talk about saving small amounts of weight, for example, but it makes a difference over time with less weight to throw around. Again, you won’t notice on short rides around town but when you’re spending tens of hours every week on the bike in increments of 1-3 hour rides, it’s worth optimizing these things.