As with anything we purchase, we want the most bang for our buck. With video games it is the same. We would like lots of content for our money. Some of the most popular games have great game play but such limited choices that there is almost no reason to play them again unless you are trying to do better than you did the first time.
The Halo games are great first person shooters. The campaigns, while fun, are fairly short. There are no side quests to get away from the main goals in the game so there is really nothing to do but follow the main storyline. Even on a harder difficulty level, everything is the same just harder to kill. If it were not for the online play, this franchise would have died quickly.
Heroes of Might and Magic
Heroes of Might and Magic has a large campaign to follow so the content is good but once you finish a section of the campaign there is no reason to go back and play. All of the maps stay the same and there is not much difference in which character you play. While you could handle the strategies slightly different if you started over it still is the same basic principles in the game, more and tougher troops with better spells wins.
Final Fantasy offers little in the way of replay value since there is not much to do in the game but follow the main story line. You can wander a bit to fight a few more things but there is little to do besides the main story. Since you only get certain people in your party at certain times, there is no reason at all to replay the game. Everything is basically the same when running the game again.
Halo Wars like Halo has a straight forward campaign. No side tracking doing anything other than the maps that are required to beat the campaign. While you could go back to find all the skulls for the achievement, the maps and fights are the same and there is little the game has to offer that would make you want to play this over and over.
Warhammer March of Chaos or Warhammer Battle March
If there is anything worse than have a game with little replay value then it would have to be having the same game renamed so you buy it twice. The computer version March of Chaos was renamed for the X-box 360 to Battle March. This is the exact same game and either version while fun has no replay value unless you want to replay the exact same battle over and over to perfect it.All of these games would be so much better with random maps in the case of strategy games or random monsters and side quests in the case of shooter and RPG games. We need more companies like Sega and Bethesda whose games are in depth and have many random factors in them.
Source: My personal experience