By the title of this thread (and the other where I guess you got the subject up before you post), I wasn't sure what you were talking about.
Yes, Lionel made the less detailed and more affordable 027 line of trains, but I personally hardly consider them little - though they are smaller in size. they have a charm to them that is all their own. And you are right - especially on a smaller size layout - that a string of 5014 box cars and 6012 gondolas can look pretty impressive in their own way.
I personally repaint many of these smaller cars by Lionel, MARX and K-Line and with a little attention to decaling, can look pretty darn good. I always get surprised looks from other train guys when they see these smaller cars in CSX, Norfolk Southern, BNSF, CP Rail, Conrail, etc.
I'd be willing to bet that after running these cars on your Christmas layout, your feeling for them may become a little stronger. They may be "little" cars, but they're just as capable of making BIG memories as any other.