When you think about it, the Eagle was one of the best designed ships in universe on a long term scale. It has a reasonable acceleration curve, a strong cargo capacity, good point defense by canon standards, and sufficient drop collars to be useful at its mass. Its firepower is quite fierce. Most importantly, it is easily upgraded. Sure it needs a good defensive boost, and sure its guns could use some upgrading, but all in time. Unfortunately, it was not given that time. Generation 1.5 upgrades to it, and other ships could have made them ferocious. I will not provide any fan designs, and there are numerous ways to rework the ship, including further exploitation of its handy cargo capacity. It could also be redesigned to work around generation 2 warships differently.
By comparison, I would have given the Fox some extra PD, and written it off as a light transport when the generation II warships started to appear. Not a shameful task, but probably not the role envisioned when it was harkening a new age of aerospace dominance, or to at least provide a measure of balance against the clans. Or perhaps the Fox is symptomatic of transport warfare mindset, rather than a more holistic system that combines that with aerospace supremacy.
It is unfair to overjudge the first warships pushed out by any of the houses in centuries, because much of it was a learning curve. The differences between the Fox, Impavido, and the Kyushu do make for interesting conversation. I believe that only the Impavido was actually designed to hunt other warships.