what was the point of making them prodigies?

Is there a deeper meaning to it all I am missing or was it just something quirky Wes Anderson added just for the sake of being quirky?

It gives them something in common with Royal, their dad, which ultimately allows them to reconnect with their father. Richie finds it easiest to reconnect with Royal, followed by Margot--Chas has the toughest time although all three are estranged when the movie opens.

By making them prodigies it gives them something in common with their dad despite the estrangement. All were very successful at something in the past but are now resting on their past laurels--as is Royal, who was once a successful lawyer but apparently hasn't practiced law in many years. Although estranged, the life of Richie in particular closely resembles that of his dad when the movie opens. Both are living in unusual, but somewhat luxurious, circumstances--Royal in a hotel and Richie on a boat--apparently living off money earned back when they were more successful. Of course, Royal's running out of money, initially concealed behind his false claim of cancer, is what sets the events in motion.

Their specific past careers are less important than the fact that Royal shares with all three children the fate of having once been really good at something but later losing it. That commonality reunites them. Other characters such as Eli (despite his substance abuse), Etheline, and Henry still seem to have successful careers, but they don't have the same need to reconnect with the adult Tenenbaum kids.

I think it's meant to show why they are detached from normal society.