It's not because those games were just particularly amazing, well-written, and well-constructed. It's because those were the games that we grew up with. Those of us in their 30s and early 40s are the ones currently dominating the industry, and we grew up playing King's Quest IV and Monkey Island and Loom and X-Wing etc. We have a fondness for those now because we were kids and those games were the world to us.
Same reason most of us love Voltron and hate Power Rangers, even though they're damn near the same thing.