One big difference is that in an airplane, all two members of the crew have the same certificates. As far as the the regs are concerned, a dripping wet ATP can buy a 747 type and legally fly it.

For seamen and officers, there are a number of ranks and tonnage certificates. Even Master has several different levels (limited 100 tonne, 100 tonne, 500 tonne,.... up to unlimited).
Seafarer's professions and ranks - Wikipedia, the free encyclopedia.
Approved Courses - USCG National Maritime Center
Each of them require experience and/or schooling to move up.

So, IMHO, if the regs were to change to something like:
Pirvate, Commercial (to 12,500lbs), ATP 40k lbs, ATP 100k lbs, ATP 300k lbs, ATP unlimited
AND
If our planes still required Pilots, Copilots/FOs, Second officers, Engineers, and Navigators,
OR
If a pilot had to go from a B1900, to a Saab, to a DC9, to a 737, to a 747
THEN we might be able to compare the pilots to seaman.