Now, my purpose behind this is not to ask Latias to be retested in 4th gen, but to make everyone think of their logic behind this now. Back in 4th gen, we can considered Specs Latias to be broken even those counters/checks listed. However, now in 5th gen, the majority (as demonstrated in the vote) considers Specs Latios, a Pokemon who is arguably better than Latias in said role not broken in the face of the same counters (minus Nattorei, but Latias has less power output, so it kind of evens out). Doesn't this sound like a contradiction to anyone? I'm aware that 5th gen is vastly different to 4th gen, but there are enough similarities between the two scenarios (i.e. checks/counters that exist). If anything, Latios should be more broken this gen with the addition of Psycho Shock to blast Blissey to hell with (the one Pokemon that Lati@s had to Trick to beat last gen), and the fact that the current metagame is a whole lot more offensive, meaning Latios can kill things easier and make even more situations for a teammate to sweep. So if we follow this logically, if you think Latias was broken last gen, then you should also think Latios is broken this gen and the opposite applies if you disagree. However, the community seems to contradict this. Hopefully this should be corrected as the metagame stabilises, but this is one major contradiction I'm finding very hard to swallow.
I believe that your post has inside the answers to your questions. This metagame is a lot more offensive than the 4th Gen one (especially after Latias and Salamence were banned). There are many new offensive threats in this generation, some of them are naturally faster than Latios (Thundrus, Tornadus, Excadrill during SS, clorophillerls on sun teams, speed boost Blaziken) while others can use a -2 SpA Latios to set up and generate dangerous situations for the Latios user. Add to this that we already got a plethora of counters\checks during the past generation and you'll understand the reasons why people are voting it OU.
I've always been convinced, even back in 4th Gen, that the Lati twins were not OP without soul dew and I'm glad that most players are starting to play around them rather than trying to eliminate them from the metagame.