Eliminating negative customer service experiences is more important than providing positive ones. People remember the negative stuff and talk about it – that's not a trait limited to people on this board
. There are two problems with having staff assign seats on the train.
First, passengers are used to choosing their own seats, either when making a reservation (most airlines) or walking on board (Southwest, corridor and commuter trains, and pretty much every other form of public transportation). Taking that choice away is annoying at best and upsetting at worst. A friend of mine is a "never again" after what he perceived to be an unnecessary and unpleasant such encounter with staff on the Starlight. I had the same reaction the first couple of times I was told to sit somewhere I didn't want to sit.
Second, customer service skills (or perhaps willingness to use them) vary widely among staff. It's all about customer perceptions. What a staff member might think is a perfectly reasonable way to give instructions to passengers can be perceived as being told off. And then there are staff who do bark instructions at passengers.
If you let passengers choose their own seats and then deal with any problems that do come up (which seems to be the de facto standard on the Starlight in recent years), there will be fewer potentially negative interactions with staff, overall.
Another benefit, which might horrify some on this board, is that it'll help normalise long distance train travel. The more it resembles the experience people have on other forms of transportation, particularly planes and other types of trains, the more likely the expectations of new and/or infrequent riders will be met. That's how you attract and keep new customers, which Amtrak needs to do.