Coming late to the party to give Clem a ride home..
The internal baffles in a loudspeaker can server a couple purposes. The most common is stiffening the box to attenuate major panel resonances and force the remaining resonances to higher frequencies, preferably outside of the most sensitive hearing range. The BBC school of speaker design goes the opposite way, using relatively thin cabinet walls not extensively braced but instead heavily damped with bitumen or something similar, driving resonances lower instead of higher. In either case, the front face baffle to which the drivers are fastened is preferably thick and solid.
Another purpose can be to create separate internal spaces for different drivers in a multi-driver speaker, isolating them so that the back pressure from one driver doesn't intermodulate the movement of another. That's not necessary if one of the two drivers features a sealed back chamber, which is common with tweeters and sometimes midranges. And is obviously not necessary with a single driver speaker.