A pick pocket of 40 means you can strip every small item off of an opponent as a free action. That's amazing.[/qoute]
And provoke attacks of oppurtunity if you try to do it in combat and don't have improved unarmed strike. And face the fact that your opponent can oppose with spot, and will probably be very unhappy with you if he notices.
A jump DC of 40 means you can... Jump 10 feet in the air. Or 40 feet across the ground as long as you double move to do it. In a world where it takes a 3rd level spell to fly. Fly. And a 4th level spell to fly ALL DAY. A jump DC of 40 is lame.
Here the problem is with the spell, not the skill. Fly is equivalent to having a +100 Jump, Climb, and Balance check. Something is seriously wrong with that being a 3rd level spell. I'm almost certainly going to make Fly a 4th level spell in my next campaign, and a spell that let you fly all day would be in the neighborhood of 7th level. I want to have Flying Carpets reoccupy that niche of being the archeatypal wonderous item and not merely a yawn, and I want Balance, Climb, and Jump to be useful even into the mid-levels because that's the point that the first start being able to do extraordinary things and not merely protect you from ordinary challenges.
An intimidate check of DC 40 means that you MIGHT make a foe friendly for as long as you are actually with him. And afterwards he hates you. Or you can give him a minor penalty for a small amount of time. Ooooo.
You should see my charisma based combat feat tree. Or if that isn't your cup of tea, an intimidate check can do something a DC 40 Diplomacy check can't do - make an NPC go against his own interests even when both you and he know that you are making him go against his own interests. You can use intimidate even against NPC's with high levels of sense motive, and even when your bluff fails. Besides, not every character has access to diplomacy and bluff.
A disguise check of DC 40 means you can fool people who are not particularly perceptive. If you're changing much beyond minor features, you've probably ROLLED more than 40 just to hit the DC. And your opponents are getting sizeable bonuses to their rolls if they have a clue who it is that you're supposed to be.
Disguise is not going to be that useful outside of a campaign that features alot of roguish intrigue, but I've definately played characters in earlier editions of the game that could have made alot of use of it. If you've ever had a character that used multiple non de plume's, then I'm sure you can see the point of the disguise skill
A balance check of DC 40 means you can walk a tightrope. Is that yawnarific or what? That means that basically every circus I've ever been to has had someone with a skill check bonus of at least +30! Hell, it means that I've got a skill check bonus in that region. That's just craptacular.
I've covered the physical skills already, but I just want to point out that walking tightropes is not the real point of this feat. The point is that you can descend the slippery broken staircase in the dungeon without fear of plummeting to your doom. You can climb the crumbling path to the abandoned monestary without 'wasting' magic and without taking the 100' falls. When the geyser goes off in the volcano while you are walking on discs suspended by chains, you can keep your balance and keep yourself from tipping into the pool of boiling mud. You can fight on the moss covered rocks at the base of the waterfall without being swept downstream. When you get in a fight with the monstrous spider on the breakdown dome in the cavern, you can move and fight without tangling yourself in webs or tumbling to the floor below. You can charge up or down a steep slope to close with the archers, without unheroically falling on your face and making yourself a target. In the lair of the Frost Giants, you can run across the ice without sliding into the glacial cracks.
Basically, if your DM limits the encounters to occuring in 30'x20' rooms with level floors, this skill is useless to you. If the DM is more like me and tends to have encounters occur in environments that are as fantastic and dangerous as the monsters, then you'll be cross classing into this skill just to stay alive.
A spot check of DC 40 STILL won't let you see anything outside of the lit radius of your candle.
Which makes me wonder why you are relying on a candle as your light source. And if you think Spot is a weak skill, I don't know what game you've been playing.