No, it is because doors take up a lot of space. A typical door is 3 feet wide, and requires 7-14 feet of empty space to operate [0]. You can't place any furniture, toiletries, or luggage racks in this space. For a typical hotel room of 300sq feet, this "dead space" represents 3-5% of the room. Removing the door allows hotels to decrease the size of each room, and fit more rooms on each floor, increasing profit.

This is why many newer hotels choose to sliding doors, which barely take up any space, or just remove doors entirely.

[0] For a door of r=3 feet, A door swings a minimum of 90 degrees, which takes 3.14 * 3*2 / 4 = 7.065 sq feet at a minimum to 14.1 sq feet to operate.