If we were redoing Ethernet I wouldn't mind removing the CRC completely. If you want end to end reliability you should do it in the layer above ethernet. If you want link per link packet validation in a network we've already been layering advanced FEC algorithms at the physical layer for high speed Ethernet. The advantage of the latter being it's both optional and replaceable without requiring even more dynamic bits or redundant functionality in the layer 2 packet. Then on MTU make it a 32 bit field instead of a 16 bit field in case anyone wants to make hardware that supports more than 64k in the future.