Organs without cases were fashionable between 1930 and 1960, approximately. Not such a good idea because the pipework gets exposed to dust and falling plaster, also because the sound easily gets dispersed in all directions. From a purely musical point of view, there are good and bad ones, and the manufacturing quality had more to suffer from the economic crises and wars than from the absence of casing. Still, such organs often get associated with "bad quality" without further checking, which is stupid.
This one, in Lille, is from 1950. It is a very solid organ with good tonal qualities, and one of the feww organs here that were recorded by first-rate organists (Gaston Litaize in that case, and several times).
What you see is only the pipework of the "choir" organ, i.e. a smaller set of pipes located low at the gallery girder, in the back of the organist who faces the main body of pipes. The choir organ is played via the second manuel (out of three) in this case; usually (17th-18th centuries) it would be the first.