I think the short courses are good for what they're designed for, which is ticking a box. If you already know what you are doing and just need the bit of paper to confirm it then it's all good. The same as with the 17 edition course, which is 4 days pretty much everywhere. If you already know 90% of it then that's all you need to fill in a few gaps, refresh everything you already know and iron out any bad habits, then prove that you know enough with the exam at the end.
The danger is people going in with no experience and expecting to walk out knowing what they're doing. People come from all sorts of different backgrounds so some will be more suited to a short course route than others. I have also seen plenty of sparks with 30+ years in the business who spout some right rubbish. As many have said, idiots are idiots whatever their background or experience.
I can see why people could be annoyed with the way some of these short courses are being sold (ie, time for a change of career? , come do our electrician's course etc) but don't think that everyone who's done one isn't perfectly competent to do the work they are doing as this is one of very many factors that make someone good or bad at their job.