So we can't sacrifice power for versatility? Trying to come up with a way to have a decent suite of illusion spells without having to devote all time in existence to researching them...
No, you can't sacrifice power for versatility. Read the description of spells again - their strength is ease of casting, their downside is that they are very specific. They are, basically, frozen rituals.
You can always do a ritual if you are unhappy with the spells you have, or need more flexibility.
