I'm not sure the conditions that you were using the 554 in to come to this conclusion, but just wanted to offer my perspective so that someone doesn't get the wrong impression or atleast to offer another contrary experience.
I find this statement not to be accurate.
For it to be so, the glass would have to be inferior to the 77 series, when in fact it is not. It is actually better. There is no distance that is a limit fort the clarity and sharpness of the 55 series, wether the previous generation or the new. Poor lighting conditions will effect the light transmission and the limited FOV on the previous versions are limiting factors, but sharpness at distance is not one.
The new 55 and the Swaro ATC series are both most certainly worth carrying if you need a lightweight spotter and don't need the best low light performance or magnification above 40x. In fact I've used both the 553 and the ATC on multiple successful sheep hunts, both Dall and Bighorn.