Hi Daniel,
I can see your point as DMU's do appear to be self-contained and better value for money. However, I think you will be hard pushed to convince the majority of forum members that they are better than a loco and separate coaches. Personally if I was modelling modern day British railways I would want DMU's but I would also try and find an excuse to have a loco-hauled train.
P.S. Please excuse the Man Utd. supporter.