I don't think that the scenery through that part of Germany is that great, but it's a whole lot better than the insides of airports, which is most of what you will see if you fly. Flying time will be short compared to the time you will spend going through security and waiting to board, etc.
Pricing is very comparable
Where are you getting your rail prices? German Rail doesn't show one going through Frankfurt and arriving in Strasbourg at 16:12.. The connections that German Rail show arriving at 16:12 go from Vienna to Strasbourg via Stuttgart, and they are faster than the connection via Frankfurt. RailEurope does offer a connection via Frankfurt, arriving at 16:00. Is that the one you mean? They want $230/person!
You can also book Vienna to Strasbourg via Frankfurt on TrainLine (formerly Captain Train) for 121,90€/person.
There is a rail connection leaving Vienna at 7:30, changing at Salzburg and Stuttgart and arriving in Strasbourg at 16:12. Because both ends are outside Germany, German Rail does not offer an online fare, but if you take the same trains from Vienna to Karlsruhe, Germany, the last stop on the ICE before Strasbourg, the fare is 78€ for two people booked as a Savings Fare from the Bahn. The Savings Fare on the same ICE from Karlsruhe to Strasbourg is 38€ for two. That's 116€, total, for two for the entire trip.
You can book a single ticket via Stuttgart on TrainLine for 68€/person (136€ for 2).
And with a little manipulation and somewhat different trains, you can go from Vienna to Offenburg, Germany, across the river from Strasbourg, for 78€ for two. If you leave Vienna at 7:30, youi'll get to Offenburg at 16:24 and have 10 minutes to make a one platform change to the local train to Strasbourg arriving 17:04. The fare from Offenburg to Strasbourg is 17,60€ for two, which makes the entire trip less than 96€.
How does that compare, pricewise, with flying?
Edit: I started my post before Russ posted his. I didn't know about the pass for 9,30€. That would make the trip less then 90€. The connection in Offenburg is from track 1 to track 4. Offenburg is an unusual station, with track 1 all alone next to the station building but sharing a platform with track 2. The platform change to 3/4 is down the stairs and up the next set of stairs. If you have to take time to go into the station building to buy the ticket to Strasbourg and miss the connecting train, the trains to Strasbourg run every half hour.
You can buy the full fare, fully flexible, 17,60€ ticket from the Bahn online and not have to take time in Offenburg to purchase a ticket.