It's kinda funny, isn't it...that "useless" 1st level
Charm spell used to hold a person of average intelligence for at least 3 weeks if they didn't manage their saving throw the first time, and longer if subsequent saves were failed. With 3E and its "back to the dungeon" design, the duration was reduced to 1 hour/level, which means less than 5 days for a 20th level caster. So from being able to hold sway over the "normal" part of the population for weeks and months with a measly 1st level spell, or ingratiating itself into any court, building a web of friends and allies, an Ogre Mage has been reduced to trying to sway a PC or an NPC over to his side for 9 hours.
The "useless" 1st level
Sleep spell used to be a holy terror for NPCs who, except for the few important ones, simply had no "NPC class levels", or HD higher than 1/2 or 1, which meant 4 to 8 commoners simply fell to sleep (for 5 minutes per level, by the way, not the 1 minute/level pseudo-combat spell it is in 3E). With one swoop, an Ogre Mage was able to send the whole militia of a village to sleep and butcher them where they stood, while the villagers had to watch, while today he can only blow off his
Cone of Cold before running from the veteran warriors or the high-level commoners with pitchforks.
So yeah, of course, if you power down the abilities of a monster due to the new rules, and then you don't recompense said monster for the loss of power, it will look stupid. Maybe it would be a recommendable exercise to look at
why the monsters in the 3E MM are weaker, compared to their former selves, before going ahead and complaining that they are totally useless and that it's unfathomable what reasons there were for their creation as they stand. In many cases, the MM1 monsters were taken from their earlier-edition counterparts modified only slightly, while the rules for the powers were changed drastically to focus more on rounds-long combat and on de-escalation of long-term nasty sideeffects.
That "new" Ogre Mage would make a great new monster, as a magically endowed Ogre leader, but the "old" Ogre mage was a completely different beast. If you want to give the Ogre Mage a semblance of his old power back, grant it something like
Greater Sleep from
The Book of Eldritch Might, that puts 4d6 HD to sleep and is capped at 10 HD creatures, and grant it
Charm Monster for the longer spell duration. That way, it definitely is worth its CR of 8 and can go back being a manipulative and scary opponent for the PCs as well as a terror of the countryside.
Edit: and my apologies to Pants for not reading his post, where he brings up a few of my points and offers a similar solution. That's what happens when you click the "New Answer" button too fast.
