Mostly what hon3ynuts said, plus considering UKF is a standalone faction in a DLC.
Balance wise, most of time you see factions balancing each other, OST vs SU; OKW vs USF but UKF got no counterweight and its current design has migrated far from its original one, UKF is no longer a emplacement faction but a semi USF+OST mixture.
I'm not arguing UKF are useless but picking the same two doctrines on 70% of the map pool that isn't crossing in the woods is hardly entertaining is it? Try playing against assgrens and pgrens without assault Tommies some time.
And yes Tommies now are on a similar level with grens after years of nothing but nerfs apart from two single minor buffs (tiny moving accuracy buff and 45muni Bren).
Tommies need to be more similar to rifleman OR Brits need some assault infantry if you ask me.
If I was a fanboy I would be here defending emplacements but I've actively been campaigning for their removal in place of a more USF and ost unit roster. Go check my post history, you'll see me calling out certain top "players" that have used nothing but UKF cheese to boost their ranks.