Pilots should be trained and practised to use all the "tools in the box".
On a PPL skills test if GPS is fitted to the aircraft the candidate has to demonstrate that he/she can use the basic functions of same. Equally during the navigation element of the test they have to demonstrate that they can navigate to a point just using map and compass etc.
For me it's not an "either or" argument which tends to polarise discussion as this thread clearly shows. I teach students that good pilots use strategies to keep the workload as low as possible aka "Keep It Simple Stupid". On certain occasions it might be much simpler to visually follow a line feature, on others when close to complex unfamiliar airspace it might be much more appropriate to use devices such as Skydemon etc or indeed to use a combination of both.
However as I have alluded to before much of this comes back to the quality of training which the pilot has received and also how they keep themselves refreshed with changes. All too often I find the quality of nav training is poor or even non existent. This is not the fault of the instructors who are trying to do their best with the tools that they have but all too often these days they were not trained correctly! Of course there are some exceptions but airspace infringements still occur when pilots are using GPS!