MUs having to decide in advance whether to memorize
fireball or
water breathing is part of what makes playing the class so challenging/rewarding. Rituals, as you describe them here, seem to make that trade-off unnecessary.
Yes and no. Strictly speaking you are right. But you have to look at what actually happens.
Where resource management has traditionally comes into play is in the dungeon or a wilderness trek. In both circumstances there are spells that just more optimal than others. At some levels is such that you would be crippling your character to memorize another spells before undertaking a trek or go underground.
Another characteristics that the set of optimal spells don't work the same on all monsters. So you still have to manage your mix the best you can at the beginning of the day. For example sleep vs undead is not effective.
As for scrolls there have been D&D groups I DMed with the lightbulb goes off in their head and they spend two month making dozens of scrolls before heading out.
This is based on what I seen players do "Back in the day" continuing on to the present.
So how much is really lost by allowing players to cast Read Magic at well for a cost in gp?
Now there are exploits available by allowing all spells to be cast rituals. The most blatant is healing by cleric. Basically there more of it. At least until they run out of components.
The main benefit from adopting this in a D&D campaign that the people playing magic-users well.. feel more like playing magic-users. The is one of the big difference I see when players switch between D&D and GURPS. Suddenly they are using magic in their daily life and it makes them feel like that playing a true magic-user.
Now resource management is an important part. So unlike GURPS the cost should be larger for this ability. Hence adoption of 4th edition D&D idea that components are needed. To keep it simple they are just rated in gold pieces. However again for powerful spells you can require a rare ingredient.
Finally I think the house rules is highly adjustable. You have the option of allowing only specific spells to be cast as components. The option of requiring specific components for every ritual. You can raise (or lower) the component cost. Increase the casting time. Make the encumberence of carrying components a limiting facto. All to get the exact tradeoff you want.
Again the idea to allow magic users of all level more flexibility without changing how D&D combat works.
But I totally understand if none of this works with your setting.
The reason I developed this rule is that Mages being able to do utility magic as long been a feature of the Majestic Wilderlands. Indeed there are some order of magic who can only cast spells via rituals.
For the rules I am writing I want it to reflect the Majectic Wilderlands as how I envision but I also want to be D&D as well. Not GURPS, Fantasy Hero or the other system I played. This is what I came up with.