Sure they are fun to work through, but the games of someone like Capablanca or Fischer aren't going to provide the amateur or class player with much instruction.
They will give you plenty of innovation and imagination to admire, but those things can't be taught. So...other than for the simple pleasure of playing through them, why "study" GM games?
Just my opinion...but to get the most out of GM games, play blind fols chess with them. Play out the opening, and then cover the moves, and then do your analysis/calculations and decide what move you would play, and then see what move the GM played.
It will help you learn, and understand middle game planning, and increase your end game knowledge.
Well, if your premise is correct, then clearly very few people are studying the game, much less GM games. However, book sales and Internet site records would seem to contradict this.
It's not *just* the 1600 and up players who are studying correctly and regularly. Indeed, the vast majority of chess shopping and Youtube watching is from the lower half...since they comprise the vast majority of people who WANT to get better.
And it ain't working.