The game principles themself didn't change a lot. Most resources of the huge teams creating games today go into everything around graphics. While todays games are created for the masses more than ever. Easy to learn, not to complex, and ready from or for a game console. Not all of course, but many. Beside it's consequential that there are more good old games than new ones, because there are simply many more old games than new ones, ever will be.
Personally i also play more new games than old ones. Games are a bit like movies. After i saw it, i want to see a new one. If it's a good one, i might watch it twice in a week. And maybe i will even watch it every other year, or 2 years. And i won't stop watching it before it's finished. And in most cases that's much more than 1 hour. I think it's the same for others, of course also depending on the genre they like. Needless to say, that an hour of space invaders might be enough for a while, while complex strategy-games like x-com, master of orion or master of magic will take days... Btw, complexity is indeed a measurable variable. Even though todays computers would allow more complex strategy games than the oldie PCs, the tendency goes another direction. I'd bet the most complex games are not any of those today.
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