Quote from CheethorneQuote from JussticeThe main advantage is administration.
From your description I would think that you're saying that the main advantage is that it "fixes" the format in a way that you don't think the RC is going to do, thus partially removing them from the equation.
And that's fine as far as it goes, but even if I think more cards should be banned, I would think that banning them individually is the better way to go than a blanket adoption of the Legacy banned list. There are just too many cards on it that don't need to be there and since the RC still has to ban cards on top of that list, that seems like it would be just as unwieldy. I mean, its not like most people that understand the format can't quickly list off the worst of the fast mana cards. If we wanted to ban them, than just ban them, but the RC is not really interested in making a balanced format, for better or worse, which is often very frustrating for people.
Well, it wouldn't have to be unwieldy, it's only that the RC is more or less refusing to look at balance issues. If they could look at a card like Frantic Search and make the determination that's it's not a problem the way it is in Legacy, then fine. But they are not even taking the fact of cards being banned in Eternal formats as a cue that they should be looking at it in the first place. So fast mana, <2 cmc tutors, and busted CA engines like Necropotence and Survival aren't drawing any more eyes, despite having been called out as broken by competition committees that actually look at balance.
Meanwhile, it's hard to say that the current regime isn't itself at least at this level of unwieldy, anyway. Stuff like Protean Hulk, Metalworker, Balance are just different looking bans that the recent roll-out of Sylvan, Prime Time, G-brand, and Sundering Titan. Whether the dates make sense to some or not, their time on the Legacy banlist did precede their bans in EDH. And it's hard to have any real, independent criteria for a ban like Metalworker or Balance, which just like the Mind's Desire combo pieces, are not game-breaking at all outside of 60 card, 4 max.
So essentially, there is already some evidence that the RC did at one point take cues from the Legacy bans. That itself has already created this incongruity. But somewhere along the line, the RC decided that basically any deck winning before 10 could be considered unsporting, looked at what needed to be banned to make that happen, then abandoned whatever inclination they had to look at other formats. Wrong decision, imo.