Nope, not necessarily.
I use 3 types of Scout:
CCW Scouts, in squads of 10 or 5, with a Powerfist Sergeant. A really cheap and easy way to get a powerfist exactly where you want it to go, and 12 other S4 attacks don't hurt either. Can swing an already close combat, or tie up a unit many times more effective (and expensive). With a choice of Outflank or infiltrate, they can also pull off some nasty work on tanks. Don't forget about the Storm transport option either - armed with a Multi Melta, you can really bring the pain to a badly positioned tank, even if they take out the Speeder, they have to devote even more firepower to bringing down the Powerfist as well. The extra -2 to a break test is nice, but a little hard to use properly.
Bolter Scouts, and I don't bother with a Heavy bolter because they can then move and rapid fire without losing any potential. Again with the Powerfist so they can damage anything they're likely to fight. The killing potential can be low or high depending on how good you are at rolling 4+ to hit, but frequently do a good job of softening up an enemy unit before charging, or finishing off a depleted one.
Sniper Scouts. Generally speaking, it's always worth taking a Missile Launcher, Cloaks and Telion if you can afford him. Camp an objective and hit whatever you think they can kill, ranging from MCs to tanks (with the BS6 Krak Missile) to infantry that are vulnerable to pinning. Also hysterically funny for sniping that Nob in the 30 Strong boyz unit with the Power Klaw - but the problem is that his Boltgun is still only AP5 so without a lot of luck, you're going to struggle to do multiple wounds.