You're probably right. I've always thought the Winchester .40 165gr Ranger T and .45 230gr SP and +P Ranger T were their best Ranger loads. The +P .45 is pretty hot. Spec'd at 990 fps.
Another possibility is trying to reach the spec velocity from a 4.5in barrel. Increase the load slightly, not enough to change spec, but now you're getting 871-890 depending on the gun (Sigs always seem to have slow barrels, JMO). How many LE agencies or regular folks carry 5 inch .45s? Not many. Most are carrying Glock 21s, Sig 220s, M&P 45s, something with a barrel length between 4 and 4.5 inches. I've noticed through various gel testing the 45 HST seems to be the most velocity dependent of the HST line. I've seen several short barrel tests of the 45 HST that have shown failures to expand through clothing/denim. Perhaps Federal is trying to address that because they know end users will use it in pistols with barrels as short as 3 inches. If that is the case, kudos to Federal.