It makes perfect sense. Lionel steel sided reefers and milk cars are two of their best in the detail dept.
The only drawback this time will be the hideous thumb tack couplers.
Probably a good guess vl milk cars will be in the next catalog to go with the niagara.
On a side note. Did real Niagaras even pull milk trains? I thought that was a fantasy idea for the CCII version. Just curious.