One of the many complaints users seem to have about Reach is the grenades and how they are implemented in the game. The immense amount of power they have enables users to score easy kills thanks to that power, however I don't believe a further reduction of power is necessary to "fix" grenade implementation in Reach.
If you recall the Reach grenades from the Beta, they were much more effective with a slightly shorter fuse. Despite a cut to power, and a mere fraction of a second cut off from the fuse in the release, they are still nearly as effective despite the modifications. Personally, I favor the high power output of Reach grenades over Halo 2 and 3, as Bungie themselves have stated this was to bring back that classic feeling from the incredibly powerful grenades the first Halo had.
The real problem is the fuse. It's not long enough. In Reach, throwing grenades can usually guarantee the scores of kills simply by lobbing them around, eliminating strategic use for simple kill count. In the first Halo, grenades held high power similar to Reach, but had a much longer fuse helping you flush out targets skillfully rather then simply relying on the grenade to do all of your work.
In Reach, if a grenade comes your way, once you hear it ping off the ground you a probably dead in a moment after before having a chance to react. In the first Halo, if you heard the ping of the grenade, you would go, "Crap! I need to get out of here!" and make your move, hoping to retain some sort of edge in combat instead of simply going, "Well, crap. I'm dead." And then try to regain your footing off respawn.
In short, I support a longer fuse to return strategic use of grenades to Halo, and promote coordinated offensives and player participation with the increase of a fuse as they've already received a drop in power from Beta to release, and don't need another. This instead of allowing the grenade to do all of the work for you. Discuss.