Opinion: When Pleasure Island was built it was adjacent the Disney Village shopping area but otherwise not in the way of anything. Problems only began when the whole concept of Downtown Disney was created, with Disney Village becoming the Downtown Disney Marketplace and the new Downtown Disney West Side being built west of PI.
Marketplace by its very nature has a large selection of stores and restaurants, with many of the shops filled with Disney character merchandise. The West Side has never had much to entice the majority of Disney visitors with their children. Shoppers at Marketplace had a long trek to go to the West Side. They had to follow the long sidewalk adjacent the Downtown Disney parking lots and then either go in front of or behind the Planet Hollywood icon restaurant. But either path required a deviation around Pleasure Island. Not that many made the long trek but in my opinion this was more to do with the shop selection at West Side rather than distance.
Disney decided they needed to shorten the distance and the way to do that was to "open the island". In the past Pleasure Island was closed during the day and at night it was gated and only those with admission tickets could enter. Those with admission tickets were treated to midnight fireworks and confetti each evening as well as outdoor stages with live bands and shows. There was an air of exclusivity. So the gates were taken away and only those entering the clubs needed a ticket. This led to roving bands of teens hanging around which upset guests. The band stages were removed to eliminate the attractiveness to teens but it also eliminated most live band performances. The exclusivity of Pleasure Island went away.