Her comment when I mentioned my weight gain once was 'Oh your OB must be really old fashioned, nobody weighs pregnant women anymore'.
My midwife actually asked me to weigh myself at my last appointment. They don't make it routine as such, but they like to know your starting weight and get you to weigh yourself a couple of times during the pregnancy just to make sure everything is ok, and you are not putting on too much or too little. That way it gives them an idea as to whether you might need more info on nutrition etc.

Anyway, I think the thing with internals during pregnancy is that they have gone the same way as episiotomies and shaving of the pubic area - once upon a time they were done routinely, but in recent years of evidence-based practice, it has been shown that they are mostly unnecessary and in some instances are even harmful. Basically, in the majority of cases there is no benefit by having one, so they are not done.