how do 3.1 soundboard handle 2.0 audio?

If on television I watch mostly news and YouTube, is it worth getting a 3.1 soundbar or should a 2.1 system sound pretty much the same? I'm guessing much of the audio will come in mono. But I understand that the soundbars have their "filters" to make the most of the audio. Is the center speaker still used in 2.0 audio signal?