I'd have to agree. Amaram would have killed everyone else anyways. It would have caused too many questions as to why he got only the shardblade and some lowly darkeyed got the plate.
Also iirc the Shardplate would be enough to change his eyes, and as long as he married a lighteyed their children would most certainly be lighteyed. Heck even if he married a darkeyed they could still be lighteyed. Rosharian eye genetics are weird though, so there's no telling what nahn or dahn they'd turn out.