For many years, players have served with their forehands from the backhand side of the table.  I often have asked club players why they serve from that position, most have no answer. 
 
Professional players have traditionally served with their forehands from the backhand side of the table so that they can play a strong forehand on the first ball.  They want to bring out their biggest weapon first (the forehand loop).  This was very true during the 80s and 90s.  Many loopers were very forehand dominant.  Now, professional players are very balanced with backhand and forehand attacking from both sides.  Good examples include Zhang Jike and Fan Zhendong. 
 
If your style involves attacking with both backhand and forehand, then I encourage you to Mix It Up!  Sometimes serve from the backhand side, sometimes serve from the middle, and sometimes serve from the forehand side.  By serving from different positions, you can accomplish several things…
 
#1 Force your opponent to change his ready position
#2 Use better angles
#3 Better setup various weapons such as forehand loop, backhand loop, flip, and smash
 
Before you can properly apply these variations in tournaments, make sure that you experiment in practice matches.  The goal is to MIX IT UP with good variation while maintaining your consistency.