Their use is too bad than before. These spells are not needed to exist even I think. So I'd like to suggest this change.
DC check of Knock, Detect Doors and True Seeing spells follow your spellcraft. Maximum DC is increased by 4 every your caster level. When used by wands or scrolls, It follows highest one of your UMD or Spellcraft, also Maximum DC follows caster level of the magic item you activated.
Ex) Wiz 1, Spellcraft 10 => DC 4 (Max 4)
Wiz 10, Spellcraft 20 => DC 20 (Max 40)
Wiz 2/Clr 18, Spellcraft 44 => DC 8 (Max 8)
Wiz 20/Magister 5, Spellcraft 80 => DC 80 (Max 100)
CLR 20/Exalted Angel 5, Spellcraft 60 => DC 60 (Max 100)
*Divine is only available to True Seeing.
Ex2) Knock Wand (Lvl 10), UMD 20/Spellcraft 4 => DC 20 (Max 40)
Dectect Secret Door Wand (Lvl 5), UMD 5/Spellcraft 20 => DC 20 (Max 20)
EX3) True Seeing will give you +10 additional DC.
If it's applied, I think Dice should be 1d10, not 1d20 like current, though I'm not sure of this part.
anyway, this change will make them revived.