Is thumbgen(or equivalent) necessary?

I was under the assumption that if all of your network stored media was in properly named folder/file format that the WD TV Live would automatically download the correct meta information, available fanart, etc.  I see an awful lot of talk on here about thumbgen and Mojo(not sure what Mojo is) and its making me wonder if I’m wrong.

Mojo is a theme: http://community.wdc.com/t5/WD-TV-Live-Streaming-Discussions/Mojo-for-the-SMP-Updated-9-29-12/m-p/287022/highlight/true#M840

No, Thumbgen is not necessary unless you are using a theme that requires Thumbgen to display the backdrops correctly for that theme.

thanks!