Probably to reduce weight.
I aways figured it was for looks but I think Yogi has the correct answer.
Would a laminated wood handle weight much less than a handle with the same wood, but solid (both not hollowed)?
I still think Stiga Nostalgic handles are laminated wenge, if it is, would be a good a example of laminating for weight loss. I believe Yogi could confirm if it is laminated or not.