I talked to the former exec who was forced to make the choice about this once. Said that travelers, particularly international and lower-income ones, wanted to guarentee they'd be able to see certain characters (the ones you always see, like Mickey and Friends, princesses, and so forth, maybe a movie tie in or two for something recent). Roaming characters, as much as he loved them, prevented that. It was a very unpopular choice with fans, CMs, and others, but greatly popular with the guests where Disney makes most of their money in Orlando (as they do now). People that are not APs, IE the group Disney notes will spend more, albeit far less often that APs or locals, will spend more money if they know they'll be able to see their favorite characters, even if it means a cookie cutter linear experience.
The only character I've lined up to see in the past decade was Baby Groot - because how could I not?