This thread made me think about something I was going to mention long ago but I kept forgetting about it because it seemed like a minor issue..
They need to cover a larger spectrum of units. This is absolutely needed in order to get some better doctrines in already. Better not as in overpowered, better as in more variety and options for possible doctrine bonuses.
I think the allied doctrine design is fundamentally flawed by the names they were given. As an example, Axis has Terror. This can mean anything from tanks to support weapons to infantry. And guess what? All those things are buffed massively in that doctrine. Now look at Armour. The name already bottlenecks you into armor buffs because it would seem illogical to buff something else.
It might look like something minor, but it single-handedly decides what kind of units from your unit roster it's going to buff. Honestly they should be renamed so they aren't too focused, perhaps Infantry could be something like Breakthrough Tactics, Armour Offensive Operations. It would NOT force the doctrine to only buff infantry or armour units, but rather promote a healthy mix of them because all are useful and receive buffs that are inline with the doctrines theme.
After the new name was decided, you could slowly go through the doctrines and add alot more buffs that you would otherwise not be able to add, resulting in a more exciting doctrine because you are NOT forced to build an entire company of Airborne units just because the name (and the doctrine buffs) are telling you to do so.