eamon
Explorer
In my experience, people are quite reluctant to pay XP costs. Also, that's just one level; you'll want to do it more often eventually.Look, even without going all splat book, you can pretty much eliminate the rogue fairly easily. A 5th level wizard needs 5000 xp to go to 6th level. Lets say he takes craft wand (a bonus feat) and gives up 10% of his xp for the level - 500 xp[...]
Not that I'm really disagreeing that wands are a good idea - but usually people would rather pay the extra factor 2 in gold rather than the XP cost. Not to mention the fact that that much gold is huge at those levels. 25k in gold? That's a little more than the full wealth-by-level loot a 12th level character can expect to find.
Also, if you want to find traps+disable them+open locks+sneak/scout, you're looking at quite a few spells, and not just from one class. You'll be paying a lot to really replace the rogue's skills.
I think the problem here isn't the caster so much as the rogue. Just like most people don't want to play "just" a healer, a rogue-as-gizmo-engineer isn't that exciting in play. And it's a little tricky at the table anyhow because it's often not a group activity. Basically, the rogue is screwed because he forces the DM to choose between making only him happy or making everyone else happy. And so naturally the kind of stories that emerge from D&D's traditional cooperative storytelling don't favor the rogue.
In 5e, I'd hope that skills are a recognizable feature of the rogue, but not an exclusively defining one. It just doesn't work well. And if skill advantages are broad enough and flexible enough, then a duplicating ritual or spell isn't so bad; particularly not if there are some downsides like duration, cost and (for knock) the noise.