Simple power indicator as far as I can tell looking at the PCB. Non-essential to operation. The trace, resistor or LED may not have the best connection, I wouldn’t worry about it. It was probably included for aesthetic reasons. People like shiny lights when they plug things in to make them feel like something is happening. Probably not a bad idea to stick the PCB into a metal case (like the ones rtl-sdr.com sells for $5) for ESD protection and extra cooling anyhow. Doing so negates the need for a LED at either rate.
