Yes, unfortunately that is correct. The added value is a Princess rep to greet you in the airport, handle your luggage, a bus transfer to the hotel, a Princess rep at the hotel throughout your stay to answer questions, and then the train transfer to Whittier. The tracing transfer is often not available through Princess without booking a package, so that is the best added value I see. That train ride is beautiful and takes you through a section that cars don’t get to see.
To save some money, though, you can book independently, take an Uber to your hotel, and book the Alaska Railroad train independently.
It really comes down to how you prefer to travel.