I suspect the problem is less with the 5 hours training and more with what attitude students come out of the course with. I suspect some people will find a way to kill themselves regardless of what they're taught or told, no matter how many times they're told that turns out of cloud are an emergency procedure, just like autos etc.
I think the 'instrument appreciation' time can be useful, if done right. For me, when I did my PPL, I came out absolutely damn sure I didn't want to fly into cloud, because I was scared silly by what I expected the outcome to be. Much later, doing an IR, even having prepared and spent hours in a sim, the first time I took a Bolkow into cloud for more than the time it took to pop above the layer was interesting, and I'm really, really glad I had an instructor in the other seat to catch the initial wobbles. IFR flying requires training, practice, and recency, and PPLs should be made absolutely aware of their deficiencies in this respect as part of the training (or at least, as much as possible).
Having said all that, I'm not an instructor, so I've only been on the receiving end. I believe the 5 hrs in the PPL are useful if done right, as evidenced by my instructor(s) along the way.