Yes. We definitely need a new ranking system because "Average" is currently way too broadly defined. There's a huge difference between a player ranked 1585 and a player ranked 1385.
I get frustrated when I restrict a table to "Average Level and Above" and someone in the 1300s joins. I don't boot the person because it's rude and technically, they're allowed to join. For games like Puerto Rico, that person is almost guaranteed to get last place and/or make moves that imbalance the game. I played a game a few weeks ago where the player who went before me kept choosing the Craftsman role, which allowed me to easily trade my coffee and gain tons of doubloons. I had enough doubloons to easily buy three big buildings with tons of doubloons to spare. I didn't even feel like I won that game fairly because of how the lower ranked player unknowingly tipped the game in my favor.
On the flip side, I also get frustrated when, for games I'm not good at, I restrict the table to "Average Level and Below" and people in the 1580-1599 range join. What I really want are people who are also in the 1300s to 1400s like me to join the table. A game is more fun when I play with someone who is of equal rank.
I also agree that beginners should not start at a 1500 ranking when they first play a game because if you're playing for the very first time, you are not "Average."