> because the invention languishes undeveloped for 20 years.
This could be fixed. One approach that comes to mind is to require a sub-20-year renewal process that, if not followed, terminates the patent. This might be due to simple non-execution (e.g. patents held by a defunct company, or entities otherwise unable/unwilling to pursue development), failure to pay renewal fees (e.g. you must pay an ongoing lease on your monopoly right), etc.
This could be fixed. One approach that comes to mind is to require a sub-20-year renewal process that, if not followed, terminates the patent. This might be due to simple non-execution (e.g. patents held by a defunct company, or entities otherwise unable/unwilling to pursue development), failure to pay renewal fees (e.g. you must pay an ongoing lease on your monopoly right), etc.