I agree with the idea of cost: a world-class wooden coaster is significantly less expensive than a comparable steel coaster, so the smaller parks can better afford great wooden coasters. Plus, they may choose wooden coaster more because of the traditional look in the first place, therefore being less inclined to build a steel coaster at all, if it is a choice between the two.
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Po!nt of View: A different look at Roller Coasters.
http://www.crosswinds.net/~justmayntz/thrills/index.html