To put it simply, the thought "meme" that The Watchtower is putting forth seems to be, "Construction work" is good, "Computer programming" is bad.
We had a talk a while back from Bethel rep Don McLean and he really hammered on about this. Bragging about how many JWs are construction workers and how this is far better than academic qualifications.
It's great for the WTS, free labour, that's really the point.