PW-5 type certification

I'm new to soaring and don't quite understand why so many sailplanes are registered under the "experimental" category.

Why would a glider with for which a type certificate is available, like the PW-5, be registered as experimental. It does seem like many aircraft that were once type certified have "migrated" to the experimental category. Is the type certificate worthless? More a burden than an advantage? (The type certificate ensures compliance with certain standards, there is a reason experimental aircraft cannot be used commercially.)

Question: would you pay the same for two identical PW-5 one with a type certificate and another registered as an experimental aircraft?

I realize that my question might have very complex answers, I'm just looking for a simple general explanation (if there is one).

Thanks