I think trailers hold value because, at least if properly maintained, they last virtually forever.
Also, no one cares how old your trailer is, as long as it looks good and does the job.
I bought an open aluminum trailer because I got tired of touching up paint chips on my old steel deck one, and the lighter weight makes it tow really nice.
If I ever replace my enclosed race trailer, it'll be ALL aluminum as well. No wood anywhere.
