I share the same opinion as the OP. I prefer sorcerer over wizard simply because I don't have to prepare spells. I like the idea that if I know something, it will always be available to me. The thought that there might be a situation that comes up where I need a certain spell that I know but was not prepared for just makes me feel helpless.
"So you wanted to return to the material plane before being covered in lava? Well I know plane shift, but I did not know we would fail a save and be sent to Hell, so I did not prepare it. I also already used 12 spells today, so I am almost out."
I get the situational usefulness of the wizard, but for my playstyle I feel it is wasted. Every time I rest, I don't want to have to go over my spells and have to decide what is best for the day. I am indecisive already, adding in the choice of what spells to choose for a day just complicates things and I usually choose the easy route of just preparing the same thing. So for me the spontaneous caster is the right decision.
Another thing is when I do need that second casting of the same spell. I realize that there are power stones that will let you cast another prepared spell, but what if you don't have the money for one? On my druid I might have the need to cast multiple walls of stone, or some other utility spell. Unfortunately I prepared another spell in it's place, so now I am stuck with transmute rock to mud in an area with no rocks. Maybe I will need the spell later, but if not I really could have used another Wall of Stone.
Also as a human sorcerer, I find that I know to many spells of some levels. Plus with the added versatility of the shadow spells, It is not hard to provide both utility and blasting as a sorcerer. Sure you have to be more selective with your spells, but that just means you need to come up with creative uses and can experiment more times per day.
On a final note, I find that the Psionic characters have an even better advantage over sorcerers. Same general amount of spells per day, but they can use the spell points to cast whatever they need at the time. Some days you need more disintegrates then charm persons, but others the opposite holds true. Personally, my sorcerer rarely uses 1st and 2nd level spells, but I run out of 5th regularly. If there was a way to expend 5 1st to cast a 5th, I would gladly take that route. On that note, maybe I should look into word casting (which seems really complicated and intimidating).
