I don't know if it would make any more sense, but some history might help understand the way the law came about.
When GCA '68 was being written, some wealthy and politically powerful collectors became alarmed that transactions with fellow collectors would have to be conducted through dealers, costing money and reducing the time they felt necessary for proper inspection. So they lobbied for special treatment for collectors, which included the C&R FFL. At that time, there was no 50-year rule and no blanket designation, nor did (then) ATTD begin the process. Each request for C&R designation had to be submitted separately (though it could be for a group of guns, like a special contract). Later the law was revised to allow the 50 year limit in effect today. As that begins to include guns like the AR-15, we can expect to see the already fanatic demand for an end to the C&R designation and the 03 FFL to increase.