The one thing important about veneers on speakers is to do the inside of the cabinet too. The reason is that alot of particle boards will warp overtime when exposed to air moisture and other elements and the veneer seals the particle board (MDF, HDF, whatever type) from the surrounding environment. Obviously, as speaker enclosure with warped walls will sound different over time for many reasons. I'm sure that there are less costly methods than veneering to treat processed boards, but the point is that it has to be on the inside and outside and so this will allow the speaker to maintain its performance as originally designed. So the veneer does help the performance in that way.
The other thing it does, depending on what the cabinets are made out of, is that it may minimize the cabinet vibrating by making it slightly stronger and thicker. However, some cabinets will benefit none from it. The other nice thing about the veneer and even multiple wood layerings as another post pointed out is that the resonant properties of a 1" thick board of X dimensions are not the same as those of a 3/4" board and a 1/4" board sandwiched/glued together--the two different pieces alone change things, in addition to the glue. So the veneer will act in a comparable manner of changing the resonant properties of the enclosure walls, although on a much smaller level. I.e. don't count on the veneer alone to significantly increase the cabinet's strength, the bread-and-butter of it is in the "core" materials of the walls and bracing (if any). However, the veneer does not give the speaker any distinctive sound--speakers are not musical instruments. Any cabinet resonances are colorations and only to be supressed (with a few exceptions), the material used is only a means to an end.
A loudspeaker cabinet can only vibrate one of two ways-in phase with the original sound or out of phase, the former will augment the total ouput and the latter will null some of the drivers energy. And then technically speaking some amount energy is lost in the "friction" as the wood bends in the form of heat. The latter approach is taken sometimes, and it can eliminate the what would have been colorations; however, energy is still lost and so in the case of low-frequency drivers it can give a mush sound. I'm a little fuzzy on the latter, someone may no more. There is more to it than that. The vibrations in the cabinet can cause interdriver resonances and it can cause slight rocking of the cabinet. There's also the way the sound waves propagate from the driver itself through the front baffle hitting the edges and then the transmission to the side panels, i.e. energy is getting to the side panels from the other panels in addition to through the air pressure creating its own forces. The bottom line--the veneer will do very little for the sound of a well designed cabinet. It can help a little, but not much and not in any way the morado is more desireable than tiger maple.