The square moon and sun are one of Minecraft's old defining features. People can ALREADY get round celestial objects through use of a texture pack. If you want to change them to round, do so via a menu option to use alternate graphics, or an alternate "default" texture pack. It looks like the poll is an even split so far. Don't throw away part of Minecraft's quirky charm, you'll make half your players unhappy no matter which way it goes - but you CAN give everyone what they want in this case!