I think this is a point where the course materials need to be updated for the Digital age, grad filters are very relevant to modern photography, it is simply that these days they can be applied more easily in software than in hardware. Perhaps there is a quality issue and I would be the first to admit that Cokin's plastic is unlikely to deliver the best optical qualities.
My final thought here is that I also do not like the moody contrasty skies so typical of "traditional" landscape photography made with heavy use of filters. I tend to like the slightly blown out pale skies that I see in work such as that in the New Topographics.
But hey, we are here to learn, so in the spirit of discovery I have created 6 sets of images, with and without the 2 stop grad, bracketed +-1 stop and for the three suggested scenarios:
In each case the filtered image is the second row. I have not made any adjustments to the images, simply presented what came out of the camera. Looking closely at the images the filtered sets are on the whole better balanced and more contrasty, as I would expect, the filters do the job they are designed for. The cost in eVs is just under 2, at f/4 this is not a problem.
However, coming back to my starting discussion. The first image below is as taken and without filter. It is clearly exposed for the sky and suffers from a very dark foreground
A little work in Lightroom and I achieve the image below
Compare this to the filtered image, also enhanced in Lightroom.
OK, Cokin is hardly top quality, but again I can get to where I want to go without it. I also was not using one of my best contrast delivering primes, so am aware that there is some distance to go in terms of image quality. The tilt-shift optics would have delivered a better image and taken out the dreadful perspective faults. However, these lenses have too wide a field of view and filter size to successfully use with a filter.
Ultimately my views on the use of filters do not come down to technology it is more about the aesthetic value of images requiring filters, I just don't like them very much. I do use filters sometimes, my Polar filter regularly goes on holiday with me, I even have several of them, essential for shooting in tropical lagoons.