Earlier quoted context omitted.
Short, international, neutral name, somewhat easy to pronounce in many languages.
It’s also been a popular name for decades, http://www.ourbabynamer.com/Alexa-name-popularity.html . IMO, picking one of the most common US names for a voice assistant and then skipping the wake up phrase is dumb.
With ~125k total names since the 1940's, it's not really close to one of the most common in the US; just one that was in the top 100 for 2 decades.