I also find this a fascinating discussion.
We looked at smaller subsets of content, regional specific sets etc; we looked at download size and ease of importing old routes; we looked at which assets were most commonly used. It is surprising how often a German asset is used in USA maps for example. Ultimately we made the decision to err on the side of "more is better" for the average user.
Disabling content is fairly straight forward and removes the items from appearing in-game. (Interestingly, using the filter function does this also by only showing what you want to see).
Can I ask why having 1 or 2GB of unwanted content on your hard drive is such an imposition? It has no effect on loading times or performance. Is there something else I am missing?
It's like going to the Hobby Shop to buy a few models, and being told that you have to buy everything in the whole store!
Actually, I think it's more like going into a hobby shop and looking around at the things you want to look at and not looking at the things you don't want to look at. There is no $ cost for looking.
Taking the shop analogy one step further, you're also suggesting put all the content from the store into small rooms with doors labeled Germany, USA, UK etc. To open the door, the customers then need to knock and wait for some time (~downloading) then look around to see if they wanted any of this stuff or not.
It's true that by putting everything into one big room, everyone has to wait longer at the main shop door but they get to see everything once inside. The advantage is that the route the are making at home may need one item from every room and in that case it's a real pain.
There is no right or wrong answer as there are many types of Trainz users. Classics erred way on the wrong side of things and hopefully 2009 will suit the majority of users.
Tony