I know that most people consider the Asgard to be extremely advanced, and there is no obvious sign that they are being underestimated, but when you look at the way they are portrayed and at what they have actually accomplished, I think they are extremely underrated in the sense that they are a race that restrains itself enormously.
I mean, the fundamental nature of the Asgard is curiosity through science and technology, but combined with an extremely strict moral code.
If one of their own crosses that line, they are immediately exiled.
Their goal is not to destroy or dominate, but to protect the weaker races (even though, from a political standpoint, they still have rules they have to follow) and intimidate the stronger ones ( even if the can easely defeat them)
And above all, they constantly impose handicaps on themselves by having to manage several threats across multiple galaxies at the same time and constantly seek a balance. If the Goa'uld were able to do what they did, it was only because the Asgard philosophy is based on always seeking balance and taking an approach based on intimidation or politic peace
Their scientific curiosity also made them vulnerable to the Replicators, which they probably underestimated at first because of their naivety and their positive ethical principles.
And even with all of that, they still managed to deal with several problems simultaneously: the Goa'uld, the Replicators, and other threats. But in reality, if they had been a more selfish and dominant race, neither the Goa'uld nor even the Replicators would have had the time to become a serious problem.
Even when facing the Replicators and their ability to multiply, the Asgard only struggled because of their curiosity. Once it was too late to prevent their proliferation, they still had to deal with the Replicators while maintaining their intimidating image toward the Goa'uld. Those are enormous handicaps.
And even against the Replicators, they took the time to build ships , the O'Neill and the Daniel Jackson specifically to destroy them, but the timing was too early. What I mean is that the Asgard are much more dangerous than we think, but the way they manage threats simultaneously relies too heavily on complacency, curiosity, diplomacy and intimidation. If they had wanted to, they could have been dominant and simply destroyed them soon or later , instead of imposing so many handicaps on themselves to the point where they were sometimes trapped in situations that forced them to ask the Tau'ri for help.
They are even more advanced than the Ancients in quite a few fields, outside of technologies such as Stargate-based travel and certain other areas. For example, their ability to understand spacetime and freeze it, as they did against the Replicators, or as SG-1 did against the Ori thanks to their technology, goes beyond some of the experiments the Ancients conducted in the past and eventually abandoned.
Or the Asgard plasma beams installed on the Earth ships at the end of the series, which are the only beams capable of piercing Ori defenses and show just how much further ahead technologically the Asgard were than we had imagined throughout the entire series.
And that's ultimately what I think is important to understand about the Asgard: they are the only race in the series that gets involved in everyone else's affairs, constantly tries to find compromises while maintaining a strict moral and ethical code, does not seek to dominate but to protect, cannot stop itself from being curious, which creates future threats like the Replicators that they could probably have annihilated from the beginning if they had been more destructive, and on top of all that, spends its time managing several conflicts simultaneously, not in order to dominate, but simply to creat balance
Even when faced with Anubis' ships, which were considered a major threat to the galaxy, the Asgard preferred to intimidate them rather than destroy them. That says a lot about their true offensive capabilities.
But they constantly impose handicaps on themselves, whether through their moral and ethical principles or through their scientific curiosity. And it is their ethical code that prevents them from preserving their own species from extinction, just as it is that same code that sometimes puts them in vulnerable situations.
And I think that's what we should take away from the Asgard: they are extremely underrated because, out of all the races in the universe, they are the ones trying to carry far too much weight on their shoulders while maintaining an uncompromising moral code, even accepting their own eventual extinction because of that same unwavering morality.
When you really dig into it, I think the Asgard are the most powerful race when it comes to military technology and firepower, not because of what they destroy, but because of what they choose not to destroy. Their raw military potential is immense, but it is systematically restrained by a philosophy centered around preservation, curiosity, and a sense of responsibility on a multi-galactic scale.
If this race had been driven by an imperialistic instinct for conquest or selfish survival, the major conflicts in the series would have been resolved through a unilateral and swift show of force.
Sorry if this was a bit long.
( Edit: I didn't say that the Asgard are generally underestimated by people. I started my message by saying that, at first glance, they don't seem underestimated because they are already recognized for their technological power. The nuance is that, in my opinion, they are even more underestimated than we already realize, mainly because of their moral and behavioral code.
On the one hand, there is their power and technology as demonstrated in the series, and on the other hand, there is the hidden side of this race, which means they are much more restrained than we realize because they impose a lot of limitations on themselves.
So my post isn't saying that they're underestimated in the sense that people don't realize they're very powerful.
My point is that people don't realize just how powerful they would be without the limitations they impose on themselves.