I think many 4E people have this "all classes need the same set of resources and similar numbers, power, and utility of powers" on the brain. They equate perfect equity with balance. It really is a very excellent marketing ploy by WotC to get people to think in one and only one balance mindset. If you give something to one class, you MUST give something to everyone else. It's a marketing masterstroke which brainwashes the DND gaming community into one set idea of what is fun and what is not fun. 4E is fun because it is balanced. 3E is bad/not fun because it is not balanced.
In earlier editions, the Wizard's AC sucked and his hit points sucked, so he actually was forced to either stay out of combat as much as possible, or he spent resources on defensive spells just to stay alive, or both. That left fewer spells leftover for amazing effects, so those other spells could be fairly amazing. Those spells were resources which could not be cast every encounter, so they could be more amazing.
Now that the Wizard's AC is fairly close to everyone else's and his hit points are not that far behind everyone else's, there is this idea that all of his spells need to be on par with everyone else's. Why? Because of a vanilla concept of PC capabilities. Balance is achieved by nerfing spells so that many of them have the limited duration of a single sword swing. Err, what???
So with regard to these house rules, if a player creates these types of spell scrolls, first off he is using up GP resources to do so. Secondly, he is helping the party when he uses them.
And finally, I think magic is so mundane in 4E that I have no problem making it more fantastic again. Allow the spell casters to shine as SPELL CASTERS a bit more and use other spells in combat. The spell power is the same as before and they use up monetary resources to do so.
Spell availability and duration has been throw away. As an example the Invisibility nerf flow of DND:
1E Invisibility lasts forever or until the target attacks
2E Invisibility lasts 24 hours or until the target attacks
3E Invisibility lasts 10 minutes / level or until the target attacks
3.5 Invisibility lasts 1 minute / level or until the target attacks
4E Invisibility lasts until the caster no longer spends standard actions on it or until the target attacks
It's absolutely amazing that WotC convinced millions of DND players that most spells should be one or two rounds, some spells could last the 10 or so rounds of an encounter, and that a few could go as fricking high as 5 minutes. All in the name of the one true god, Balance.
It boggles the mind how altered the DND gaming communities idea of what is reasonable has changed. This is not a dig at 4E. This is an observation how the thinking of millions of people has been changed within a year via marketing such that they cannot even conceive that their thought processes from a little over a year ago could still be valid.
The first thought when a house rule gives something to a class or set of classes: "Do you give anything to other sources, to counterbalance it?"
Instead of: "So do your players have fun with this?"