Quote from PeinIt doesn't matter if an earlier cutoff would give more decks to the format. This is an eternal format that grows every year. That means, every year new decks are coming in. It doesn't matter if a few decks are out of the format because new ones are coming in with every new set.
But the format is going to be healthier from the start if it includes earlier cards. This will increase general diversity, make more decks viable, and attract more players from both Legacy and from older Magic eras who want to get back into the game. The cards will also continue to interact with later printings to make better and more exciting decks.
More importantly, there is just no historical reason to exclude Masques/Invasion/Odyssey/Onslaught. These sets have awesome staples that are not broken but do provide a format with a lot of exciting cards and strategies that cannot exist without them.
Quote from purklefluffall those arguing that "more sets equals better" are sort of missing the point.
i mean, where do you draw the line? what if the set before onslaught or masques has "a lot to offer"... why not include that one as well?
the further back you go, the more the format becomes like a smaller legacy. with Modern, it feels like a good middle ground and has room to expand and develop through the new sets rather than relying on decks from the oldest parts of the format. that's a healthy format. wouldn't you agree?
As another poster wrote, the cutoff goes to Masques because it is historically significant and will withstand the test of time. In 5 years, people are going to wonder why the 4 blocks from 1999-2003 were not included, given that they are good sets with awesome cards, and they fall after the Reserve List.
Starting at the end of the Reserve List is a symbolic victory for those who fought against the Reserve List, and it is a historically significant moment that can justify our format forever. It is something to get excited about.
As to the format looking like Legacy lite, this is simply not true. I encourage you to check out the decks from the Overextended events on MTGO. The vast, vast majority of them are non-Legacy decks. Even with the addition of Masques, this would probably not change.
Scepter Chant, Combo Elves, Scapeshift Valakut, Astral Slide, Enduring Ideal, Living End, Twelvepost, Soul Sisters, UB Tron, Zombies, Madness, All In Red, Second Sunrise, Battle of Wits, etc. These are decks that are completely obsolete in Legacy, but they are ones that thrive in Overextended. The format is incredibly diverse and different, and this is a testament to the "earlier cutoff = more diversity" philosophy. Adding one set would not change that (Overextended has an Invasion cutoff currently because MM is not available on MTGO). It would only increase the diversity.
Quote from Pein#1 card people want from masques is probably brainstorm, that broken ancestral recall with fetches. Then #2 is probably dark ritual.
Dark Ritual gets banned. This card is broken, unfair, and powers too many combo decks. Adding one more card to the banlist from MM is not going to make it too cumbersome or unattractive, and everyone can get behind a Dark Ritual ban.
As to Brainstorm, you can either keep it or ban it. Testing would have to determine what the right move is.
Masques has so many other awesome staples to offer that even the problem of Brainstorm would be worth it. Tangle Wire, Dust Bowl, rebels, Unmask, Land Grant, Misdirection, Saproling Burst, Parallax Wave, Parallax Tide, Rising Water, Blastoderm, Flame Rift, Accumulated Knowledge, etc. These are awesome cards that add a lot to a metagame, and having them around will help out a lot.
Overall, a Masques cutoff is more historically significant and better justifies the format and its importance. It also gives more cards, more decks, and more diversity.