i agree with the existence of RR hubs in reality, in europe we have them also, brussels, franfurt, paris, etc etc, but, in reality if you bomb a track, it is something harder to repair then in civ4, in reality you can bomb a kilometer of track and it will take weeks to repair, so there you have your strategical impact for reality, but in civ 1tile of tracks are destroyed with 1 bomb, but represend maybe 300km of tracks, and like i said, in game you repair them in 1 turn if you want to, so you must bomb just massively around a city to isolate it and have a benefit of bombing the infrastructure.
sometimes, no, almost always, it is impossible to write algorithms for doing 100% reality, so, if you cannot program reality on the first place, ie railroads and their strategical impact, you also shouldnt look on the existence of hubs and connections from everywhere if this would unbalance the art of strategy. you cannot write a routine for RR which not represent the reality and then for the rules to apply look to reality and use them on the un-real routine.
i guess you're right in real its also hard to bomb infrastructure, but lets say this, in 1945 it was like 10.000kg bombs to tackle down one railway station, now it is 1 bomb(cost 10.000) where you can bomb the same damage. So one can think alot of reasons for having more then 2 connections or not, i just have the idea that, and i played alot of MP games, it is not a matter of strategy in the game, the RR are more something to keep busy your 150bombers, while doing the attack with other units.
so, because i loose alot of heavy bombers to tackle down the infrastructure, it doesnt make sence to do so, so i noticed, noone actually attacks RR because everyone knows, it doesnt have any impact, you need 200construction turns of 10cities to destroy RR which cost 100construction turns of 1city to build enough workers to keep up the Railroads. SO noone is interested in going over to some strategical infrastructure bombing campaign, unless you are so strong you dont know what to do with the bombers.
as comment on the last one, on the trade routes..for me that would do it if they were always there..but my friend is kind of a ***** in playing these kinds of games. if in civ4 there is an option of infiltrist or spies or any other kind of char able to destroy buildings in a city(targeted specific buildings) trade should not be free for everyone..there should be some building to enable it, because my friend is the kind who will use it very wisely to destroy my building so i cannot build, ie, tanks with half of my empire because he is destroying my trade buildings..which can be tactically very wise!! which makes the game more interesting for me, and i guess for alot of others too

however, there shouldnt be to much tactics, we're no generals
