I'd be happy to sign on when ETW gets a Hearts of Iron quality resource system (and an AI to manage it)
@morteduzionism - I'm making a difference between the towns and cities. Yes, city benefits for not upgrading buildings aren't as profound as towns, but one principle still applies: that I have to forgo new units b/c I want to continue using the older ones. Also, I'm restricted in my option to build "older" units, and I'm very much against limiting options as the more choices the better. 12lbs aren't even BAD units once the 24lb is available!
Following that point, because I can't build everything in London, I have to keep the arty depot in Scotland at a lower level to get the full range of units. Now what if I needed to build an army quickly? My armies are stocked with inf, a few cav, and 5-7 arty units in a combo of howizters and cannons. I don't want 24lb cannon, too expensive for my treasury. Now London is building the infantry I need (since building just cannon alone is too vulnerable (and we're pretending a french army is in Bristol)) and will be joined by the arty i'm making in scotland. oh wait! because I wasn't able to upgrade my arty factory b/c i'd lose being able to build cheaper 12lb guns, I won't have any howitzers until London finishes its queue. And since time is of the essence, I can't have london build cannon yet since the infantry are a higher priority with the French in Bristol.
Sure, its a far-fetched example but its a nonsensical restriction on the player.
Napoleon's army wasn't composed of just one size of artillery, and even more nonsensical is
That the 12lb cannon wasn't even obsolete in the 18th century! Napoleon used many of them and
it remained a popular gun well into the civil war!
So where did the 12lbers go as the OP asked? They went to the land of stupid, ruled over by Creative Assembly with an iron-hardcoded fist.
And morteduzionism, I'm not pointing the anger or sarcasm at you. That's for CA and who ever though that making units obsolete was a good idea. I hope they didn't reason that too many units would mess up the game (AUM adds over a hundred new ones), or that the AI would be more balanced with fewer units (which its still retarded). But my point is that unit construction is a choice, and replacing one unit or making one unit become unavailable is retarded. Even
if its historical usefulness expired early (pikemen), its not any reason to say they still couldn't be trained if the King wanted them to be.