The reason Walt didn't want alcohol at
Disneyland was because his vision of his park was different from what passed as "amusement parks" in his day - which is to say, low-rent travelling carnivals and the like. As you can imagine, such places were oft filled with drunks, and Walt wanted no part of that. Hence Disneyland's Blue Law.
By the time Epcot opened in 1981, Disney had had some 25 years to establish itself as a brand for safe, clean, family-friendly fun. The addition of alcoholic beverage options at World Showcase wasn't going to change that. And in the main (excluding the "Drinking Around the World" drunks that are handled expertly by security before they become too big of a problem), having alcohol at Epcot and the parks hasn't changed that brand.
I see no problem with more alcohol at the parks, as long as Disney continues to handle it correctly (which of course it always has done and always will do).
SIDE NOTE: The first time I visited Pleasure Island, I was downright aghast at how freely and openly the alcohol flowed there. CM's were selling Jello shots right there in the streets, in front of Og and everybody. There was this one station where there was this big block of ice with a little trough carved in the middle of it - the purchaser would position her mouth at the bottom of the trough and the CM up at the top would pour the liquor down the trough - the ice would cool the alcohol as it slid down. Anyway, clearly Downtown Disney has dialed things back
just a bit from those days, but still. Part of me felt like it was 1988 and I was back at Daytona Beach for Spring Break!