When I see how popular with foreign tourists the Trans-Siberian Railway is, I clearly understand how little they know about Russia and travel by train. To be honest, I've never travelled by the Trans-Siberian but I'll never ever do it because that's how I see it.
Russia beyond the Urals.
The main historical events of Russia took place in the European part of the country, hence, not further than the Urals. The Urals and Siberia were mostly the industrial regions where natural resources were exploited, some factories were situated but all the culture and most historical sights have always been in the European area (Moscow and Saint-Petersburg, towns of the Golden Ring of Russia).
What do travelers expect to see beyond the Urals?