I find it all interesting. It started off with Men of the Orient, North, East & West. So basically barbarian hordes, norse, easterners/nippon, and teutonic knights & templars from the age of romance. Then massive jump to Knights of (selector) counts, and an imperium (emperor). The gap was seemingly defined in 1987 Ravening Hordes for WFB 2e into 3rd. Empire is defined in army lists with knights panther, arquebusiers(+15th century!) , foresters, etc. Flagellants added, so emphasis on peasantry and religious nuts rather than just templar knightly religious nuts swinging their magic swords (cleansing flame, etc).
So it goes from rag tag feudal (Men of the West emplars in 1e) to full fantasy knights...WFB 2e just played what you wanted or the regiments of renown...
But then we had 'Chivalry' (the standalone card/miniatures game) intro'd in WD130 Oct 1990, taking the theme kind of back to 'Feudal' for messing with toy soldiers. Then Nigel Stillman developed a (retconned?) backstory in WD207 Mar 1997 with a code of chivalry (for Bretonnians - noting Sigmar was away rousing the tribes of an infant Empire together east of the grey Mountains). Basically to serve the lady of the lake, etc. All very Morte de Arthur...
It's like they, GW, were dissecting, chopping & making it up as they went along. And poor old Bretonnia left with just old skool Feudal look. Empire = suddenly an organised 'european-like' renaissance army - swallowing up dwarves, ogres & halflings on the way- with added warwagons, Landsknechts, tanks,& black powder (looking at you Nuln). My weird take on it. I just remember the first Bretonnia figures late mid-80s which just screamed feudal/Arthurian...