Because BS-based shooting just isn’t that effective.
1) Each model has a limited firing arc (approx. 45 degrees), and you can’t move and fire with crossbows and handguns.
So, you’re going to have a hard time concentrating all your fire on any one unit.
2) BS3 and range penalties mean you’re hitting on 5s for your first round of shooting (ie when the other guy is at long range).
3) Relatively low strength means that the other guy’s heavy hitters will still have good armour saves (2+/3+), and possibly a ward save to boot.
4) Most newer armies have dedicated missile hunters – fast units that can hit your shooters on turn 2 and/or block LOS to the melee specialists advancing behind them.
And there are additional penalties for trying to hit skirmishers.
Where BS-based shooting excels would be to take down the smaller, lightly-armoured support units that the other guy uses to control your movement (fast cavalry, basically).
Well, technically, its about:
1) Using your mandatory 2+ Great Cannon as equalizers. :wink: They help keep the big gribblies and heavy cavalry honest.
2) Advancing aggressively with your detachments – when he charges, you either flee or hold. Both work depending on the type of detachment and the distance from which he’s charging. Key objectives are to:
a) Slow him down;
b) Pull him out of position
Ideally, you use the detachments to pull advancing enemy units (heavy cavalry in particular) into a position where you can hit him in the flank with a cannonball or two...
Simply camping with detachments just doesn’t work so well - a) You don’t have much room if/when things go wrong.
b) Against some of the nastier melee units in play these days, counter-charging with a detachment just means you’re giving more enemy models the opportunity to strike back.
3) Main blocks move up and/or countercharge or hold.
Traditional Empire armies (lotsa infantry) rely heavily on coordination and static combat resolution to win combats (and games).
Trouble is:
1) Poor to above-average Ld makes coordination difficult when fear/terror-causing units are a lot more common.
2) Static CR alone just doesn’t work so well anymore (some might argue with cause that static CR alone never did work!)…
a) Shock armies can dish out enough attacks to chew through an Empire regiment with ease – they might not break you on the charge, but they’re not likely to lose combat either.
It doesn’t help that all sorts of pesky big gribblies have access to ward/regeneration saves that allow them to shrug off cannon fire…
b) Grinding armies can out-grind an Empire army.
c) Magic-heavy armies have access to excellent money-shot spells that can fry entire regiments with a single successful casting.
A combined-arms Empire army (3+ regiments of State troops with detachments, 2+ cannon, 2+ cavalry/fast cavalry squadrons) can still work pretty well against other combined-arms Empire army (and most army books released before 2008).
Playing in a moderated/comped environment? You’ll have a chance at a technical win, especially if you’re up against a less-experienced/sloppy player who’s just coasting on the strength of a new army book.
Playing in an open environment?
You’d probably do better to invest in Flagellants, a War Altar, cannon and a steam tank or two…