"Of course now most FPS games have realistic physics, and real time semi-interactive scripted sequences are the rule rather than the exception, so someone who didn't play FPS games before the Modern Warfare days might not realize what it was about Half-life 1 and 2 that made them special at the time"
I disagree. I played Modern Warfare before playing Half life 2, and I found Half Life 2 better in every way. I think the story is lot better than 90% of FPS (The only FPS with better story than half life 2 are portal 1 and 2, Bioshock and System Shock 2) sure the story itself isn't all that great (with the exception of G-man), but the way the story is told and its characters are so interesting you end up forgetting this detail. Half life 2 may not have the best physics system ever made, but in half life 2 you actually use the physics for something. I prefer the set pieces and vehicle sections in Half life 2 over the ones in any game today, because they don't take control away from you or turn it into a on rail section. The environments and the art direction are hundreds of times better than the brown and gray realism of today. And the gameplay is just excellent; there is no denial on that.
I disagree. I played Modern Warfare before playing Half life 2, and I found Half Life 2 better in every way. I think the story is lot better than 90% of FPS (The only FPS with better story than half life 2 are portal 1 and 2, Bioshock and System Shock 2) sure the story itself isn't all that great (with the exception of G-man), but the way the story is told and its characters are so interesting you end up forgetting this detail. Half life 2 may not have the best physics system ever made, but in half life 2 you actually use the physics for something. I prefer the set pieces and vehicle sections in Half life 2 over the ones in any game today, because they don't take control away from you or turn it into a on rail section. The environments and the art direction are hundreds of times better than the brown and gray realism of today. And the gameplay is just excellent; there is no denial on that.