I have noticed that in almost every board, RJ-45 Ethernet sockets are always soldered upside-down. Why are these sockets made this way? Wouldn't it be easier to make and solder them with the pins laying on the bottom?
Connector profile is often a huge concern. I think you'll find that by putting the contacts on the top and the tab close to the board, the socket can be made 1mm or 1.5mm less tall.
I think it's just as easy to manufacture one style or the other. The reason for preferring to have the tab on the bottom is that it is less likely you'll accidentally unplug the cable by something hitting the tab.