you dont have to, and certainly wont B-line one tree, besides that it isnt even possible most of the time. And some trees go very different paths so even then you wont know what an country is doing. Unless you actually know every major's nation national focus tree out of your head you probably wont have a clue where they are going anyway. The one thing they probably should remove is the progression bar of the current NF tho.
You just contradicted your previous post when referring to USA and it's war plans. If you keep tabs on the USA, and see they are focusing war plan red, you know they will be joining Comintern. As far as not knowing trees, it takes about 10 seconds to google them if they are new to you.
Example, I'm playing Germany. Obviously I'm very interested in what France is doing. Checking on them routinely I see they are now focusing on "Support The Left." A lot of these important alignment NFs are self explanatory. Even if I didn't know what that was, a quick reference check (
http://i.imgur.com/32JeCDz.jpg) and I see they are only a few foci away from joining Comintern. I know roughly how long until they are able to join Comintern based on how long the average focus takes (lets say 100 days for a nice round number). That means I have x amount of time to attack them before they are allied with USSR (a little over a year in this case).
This could be very detrimental to multiplayer games where you are constantly checking on your opponent to see how they will align themselves. Focus should not be readily available in my opinion, only through intelligence should they be revealed.