Interesting relative read...
Seems to me Lionel was honoring the heritage of the tender design? After all, if Great Grandpappy Vanderbilt was the founder of the NYC system, what better way for a toy train manufacturer to honor a significant design creator than marry it to the iconic engine of the same railroad!
Or not.
KD
BTW...MY favorite railroad...ATSF...was never enamored with Vanderbilt tenders. And my only comment to that is "Phooey!! I wish they had used some!!" I think they're far more interesting than the traditional humpty-box on wheels.
I suspect that packaging electronics-sandwiches and Chubby-Buddy speakers in a toy train Vanderbilt tender is not nearly as easy as into a nice spacious hexahedron.