I feel like they just work harder at getting input and feedback from the more casual players. After all: that's how you could hardcore players and whales.
Nobody signs up for an account and five minutes later drops $5,000 on huge stacks of Otto's boxes and Sovereign I potions. They try the game out, the play for a bit, if they like it, they keep playing, and spend money.
A casual player's passing impressions are going to provide a better idea of what's helping retain new players. I've been running a guild for several years and had a policy of basically recruiting anyone who showed up on the chat channels and said "I wanna be in a guild!" and then watched those characters go dead 2 weeks later and never log on again(I usually started booting after 8 months or so) we are talking fresh off the boat from Korthos level 3s who made it to maybe 7 before quiting.
Now, MAYBE some of those people just made new characters. MAYBE they were broke-ass kids who thought "free" meant all the functions of WoW but no monthly cost. Maybe some of them thought the game sucked and quite.
I don't know, but a long-time casual player might have a better idea about that than a hard-core, nuts-and-bolts go-getter.
First-life, first-characters face a COMPLETELY different set of challenges than third-life completionists, and I don't know if the PC cares