Usually I would agree with you, but the target market for the sound bars are not audiophiles and just your average end user who wants to use it to watch TV and movies.
Yes they can spend a lot of money on a high-end system, but not everyone can have a 5.1 system or desire to run the wires associated with it. The sound bars present an alternative, that improves sound for the tasks they desire.
The Boston excels in audio quality, which is why we gave it 5's across the board. The Sony is just a better all-in-one solution that does everything.
And in the end it is all about value, all the sound bars in the round up are sub-$500, and the Sony can even be had for under $350. When you want convenience, features with a huge improvement over TV speakers with little hassle, you can't really go wrong with a sound bar.