Why Veneer?

Veneer over particle board is far less expensive than solid hardwood. Manufacturers claim that the lesser resonance of the particle board is an advantage also.

Particle board (MDF, HDF) is more consistent and practical.

(average and better quality, not the cheapest stuff at Home Depot) particleboard is denser, more consistent batch to batch, CHEAPER, and doesn't warp or crack as it dries.

Particle board and Medium Density Fibreboard (MDF) have better and more controlled (i.e., consistent) damping than regular wood and are a whole lot cheaper, especially in the larger thicknesses common in high end speakers. It's also much easier to change the visual appearance with veneer, the basic structure is the same, just the last 1/32" is different. I'm sure the speaker would sound much different if made entirely of Oak versus Cherry. Also, the more exotic woods are frightfully expensive and in such short supply that they almost have to be used in veneer form.

Some quality manufacturers do use REAL hardwood panels, but matching, curing, and fabrication is much more costly than veneer covered particleboard. Some cheapos even use Formica or (shudder) vinyl contact paper as a covering for the particleboard. The high quality Peak InCognito that I currently own (and LOVE) go to the other extreme: cabinets are constructed of 1.5" HDF (not MDF!), which is then covered by 1" genuine wood panels (cherry or oak, as well as other choices). Thus, the cabinets are 2.5" thick, with internal bracing, too! Obviously, cabinet resonance is non-existent. These speakers are quite heavy, as well. Look for a very positive review of these gems in Stereophile in the next month or two.