4 hours isn't that long, is it? plane cannot beat that by much
Many cities it’s a nightmare to get to the airport, whereas the train station is usually central.
German trains pack as much people as possible and occasionally you can consider yourself lucky if you manage to reach your seat, if the wagon is still available to start with.
None of my train trips in Europe (Scandinavia, Germany, Switzerland) had the issues you mentioned.
In particular, the designers of the German ICEs seem to have realized over the past ~decade that people don't want to lift heavy bags overhead (especially if the compartment is too small), and that when the only other space to store them is the corridor, the corridor will be full of bags. They added dedicated luggage racks with enough space to actually fit your luggage.
In any case, that was just an example, I am not doing Germany - Portugal by train, unless forced to do so. It is more than 24h.
That's the point, we need to expand the rail network to make longer distance trips shorter, more comfortable, and affordable. Flying can't continue to be the default option.