money - our league get a £3k per year kickback for using Readers. Balls don't swing or have a great seam and are nothing to write home about. A few complaints from clubs about the price and lack of swing. I reckon I can pick up better balls for £5-6 than the £13 per ball we get charged by the league. League won't change unless somebody gives them a better financial deal, ball considerations come second.
When I played in the TVL the balls were fantastic, swung all day, big seam and stayed hard even on rock hard decks, but I doubt the TVL skimmed as much money off the top.
On the small ball thing - sits better in the hand and makes it easier to manipulate with the fingers/wrist.