IMO, stealth is always useful, and sneak attack kicks butt.
However, stealth, Search and Disable Device aren't party skills. The rogue can't use the former near the party (and scouting by themself is often suicidal) whereas the latter don't contribute much to the spotlight. Furthermore, I don't think traps are all that good for the game. They instill paranoia ("we have to have a rogue [or devote spell slots] to finding, disabling or avoiding traps"), and WotC's fresher ideas for traps don't require a rogue to fix, or even give the rogue much of a bonus. ("You get a tiny boost to AC and Uncanny Dodge." Woo.)
Most rogues I've seen play like stealthy fighters. They use stealth to try to get an extra sneak attack, but not to scout (due to the suicidalness), and once combat starts, they tumble, flank and sneak attack, competing with (sometimes outcompeting) the fighter for damage.
While many rogue skills (eg Bluff) are useable by other classes (eg bards), they're still useful for that role if there isn't that other class (eg bard) in your group.
IMO rogues are not required, but are useful.