'Cause they're just so d- - - - cute LOL. On a more serious note, they are virtually indestructable. After decades of storage in dark, dank, attics, basements, garages, etc. most of them can be set up and used immediately. While they don't have all the bells and whistles of the machines today, they can't be beat for piecing quilt tops, stitches are fantastic.
We pay hundreds of dollars for our machines today and are encourged to have them professionally cleaned, oiled, etc. periodically (annually, if used a lot). Our grandmothers would have thought she had been taken advantage of if she EVER had to seek out a repairman (where would she even find one?)

I've got a 4800 and have recently bought a Featherweight - the Janome hasn't been used for piecing since! It's a pretty good machine, but the FW is so smooth and produces such wonderful stitches. As well as looking beautiful!