Would someone please explain to me why Defog + Roost is "done better" by Latios enough such that it doesn't deserve a serious mention on Latias's analysis? Because to be honest, the few times I've wanted to use Defog + Roost on one of the Lati twins, I've used Latias. The whole point of Roost is to keep your Defogger alive longer, and I'd honestly rather use the twin with the greater bulk that can abuse that extra survivability to the fullest. Yeah, Latios has more power going for it, but you're still going to run into problems offensively when you're restricted to 2 move coverage. Meanwhile, Latias's extra bulk really does matter. For instance, Latias is only 2HKOed by Modest Charizard Y's Sun-boosted Fire Blast 38.7% of the time, which lets it stall out the Sun turns with Roost more easily, at which point Charizard Y will be doing piss damage. Latios takes considerably more damage, so Charizard Y actually has a shot at coming out on top if Latios switches into Stealth Rock and suffers a few high damage roles (unless Charizard Y has been weakened to ~80% so that Draco Meteor will be a guaranteed OHKO). Life Orb Keldeo has no chance at 2HKOing Latias with Icy Wind, while Latios is 2HKOed 89.5% of the time. Latias can switch into Breloom post-sleep a bit more easily since Adamant LO Bullet Seed (3 hits) followed by Mach Punch after Stealth Rock fails to KO Latias, while it has a decent shot at KOing Latios (there are other combinations to consider depending on the number of Bullet Seed hits and Breloom's nature/item, but I don't care to look up all of them). Latias survives Greninja's Life Orb-boosted Ice Beam 87.5% of the time from full health, which is useful if you're in a bind, while Latios is always OHKOed (or 92.8% of the time, if you're running 0/4 > 4/0). Latias can survive 4 Atk LO Landorus's Knock Off after Stealth Rock 50% of the time and all the time from full health, while Latios is guaranteed to die after Stealth Rock and still dies 31.3% of the time from full health. Latios is 2HKOed by Mega Manectric's HP Ice after Stealth Rock 75% of the time, while Latias is never 2HKOed under the same conditions. Latias can check Mega Pinsir in a pinch by surviving a +2 Quick Attack even after Stealth Rock and KOing back with Draco Meteor, even having a good chance to live on after the resulting Life Orb recoil. Latios has a 25% chance to die after Stealth Rock, and the Life Orb recoil is almost guaranteed to kill it afterwards. Latias is only OHKOed by Adamant CB Talonflame's Brave Bird 6.3% of the time from full health, which is a 62.5% chance for Latios. Latias can also switch into Terrakion more easily; LO Stone Edge fails to KO, and Latias will almost always survive the Life Orb recoil after KOing back with Psyshock. Latios has a small shot at being OHKOed on the switch-in, and it has a really good chance to die to Life Orb recoil the following turn.
I know this is kind of a random mishmash of various examples, but it's just a few specific scenarios to demonstrate where the extra bulk of Latias can matter. Even besides those specific examples, Latias's ~10% extra physical bulk and ~16% extra special bulk will come in handy every time it has to take a hit. Honestly, I could easily see where each Lati twin might have their advantages running such a set depending on the team. If you want to run Defog + Roost for a more reliable Defogger and you need the extra bulk to pivot in and out of various opponents or check/counter them more easily, you can go with Latias. If the bulk doesn't matter to your team, Latios is better due to its extra power. I can understand why you might prefer Latios the majority of the time since its greater offensive presence is very valuable, but I honestly don't see how Latios performs this particular set so much better than Latias that it isn't even worth giving a serious thought in Latias's analysis.