Again, could be reading things wrong, but a Charge requires at least two squares of movement. If I'm blowing a Daily, I'm already in Melee and, chances are, everyone else would be by then as well. It would be a great opener, but I don't generally see Dailies as 'openers', more of a 'last ditch effort' move.
Clearly, YMMV.
The proper use for a Daily varies, but many of the best are intended as openers. Sleep? Best used to open a battle. Moment of Glory? Bastion of Defense? Again, best used early so the defensive benefits apply for the whole battle. Lead the Attack is also an opener, not a last ditch effort move--it's at its best as the first attack made against an elite or solo enemy that needs to die ASAP. Many dailys are meant to be used aggressively, and frankly I prefer those, since I tend to get more use out of them than I do from "save my ass" style powers. Stand the Fallen--a clear a last ditch effort move--is a great power, but my L12 Tactical Warlord has used it maybe twice in 7 levels. During those levels, Lead the Attack has seen 15-20 uses, and Concentrated Attack (a L1 daily in his L9 slot) has seen 5-10.
Anyway, yes, you do need 2 squares of movement to charge, so properly using Lamb to the Slaughter does want a bit of coordination and setup (so does Lead the Attack, although not as much). Still, as a daily you won't be looking to use it in every encounter. You use it when you see a good opening for it, or when you see a good chance to create an opening for it.
edit: also, note that it's a melee 5 attack, which means you're not necessarily in melee yet when you use it.
later edit: to be clear, I'm not trying to convince you to take Lamb to the Slaughter--you should take whatever power you'll be happy with. I AM trying to convince you that many daily powers are NOT "last ditch effort" style powers, and shouldn't be treated as such. And while I'm at it, if I can help you see some merit in a power that you see as weak, so much the better.
[MENTION=42968]Goken100[/MENTION], I'm willing to arrange to have worked with you in the past. You'll have to had convinced me to join up with you in killing the undead, as Markal isn't disciplined enough to dedicate himself to an organization like that. He'd happily follow your lead, though, if it meant excitement and a chance to show off.
t~