I agree with the comment that said when reward cards were made soul-bound there was plenty of talks about them being unbound at some point. In fact unbinding at some point was one of the selling points. Regardless markets change and sometimes the original plan needs tweaks. Reading comments it seems as the burn ratio is the biggest issue at the moment. Some like me think anything over the cards DEC worth is an overcharge (I do see the reasoning for making it more). Others want 5X or more of the cards DEC value to be the burn.
I suggest lowering the fee to the cards DEC value but requiring 1 Voucher per BCX. In this model Vouchers give no discount, they are a requirement. Cards that hit certain leveling requirements can require less Vouchers to unbound. With MAX level cards getting the biggest voucher discount. This will encourage combining/ adds no additional DEC to the market and will give Vouchers another usecase. Since Vouchers are currently worth 3 cents that should be enough of a fail-safe in making sure the current card market doesn't get flooded. The idea above cold be tweeked to only require a Voucher but that would mean creating extra DEC and I don't think anyone wants that. I also think Splinterlands should just bit the bullet and announce that after this set RC will always be soulbound.