The randomization issue came up at UKTS too to some extent; it was a bit more limited because it was just in terms of the same scenario playing out differently but a few good points. I would at least like to see the weather optionally randomized a bit even if nothing else can be done yet. Perhaps in the flyout for a consist in a scenario under start time you can have a tickbox for "randomize start time" and an entry box for how big an error it can be. That way you can still deliberately time something to cross at a given moment.
The OPs career idea would be excellent; to generate it you'd need a complete working timetable of a week digitised somehow, and hopefully a scenario generator otherwise you'd have to add that all to the game too, although if it's already digitised then that isn't a total disaster. I would not really like to be the one to set up a WTT for a fictional route... is there anyone who'd want to do that? The only other way I can think of is setting up supply and demand metrics for each provider/consumer on the route ( stations, loading points, sidings etc ) and having the dispatcher generate traffic from that, with the understanding that you might get a scenario with nothing much happening. That might actually be doable if people started providing similar capacity metrics for their rollingstock.
I would also like to see the ability to trigger events when the player consist has passed a certain point, rather than just a certain time has gone by. I remember Tori at least also wanting it.