but its more pressure on the floor.
Not enough to worry about in MOST cases. And if the floor isn't straight and level and you shim it it's resting on the shim anyway. Four points of contact are easier to level to start with.
All the tanks in my fish room had to have shims. Fortunately I have all metal stands so a nickel/quarter/washer did the trick. I've got a quarter under one leg of the 55 stand in the kitchen. Perfectly level but still only 4 points of contact. My kitchen cabinets, professional installed and look like they all touch in all areas are shimmed. Again, when you really look at it each cabinet, since it is shimmed, has only (say it all together now) 4 points of contact.