Now, I haven't read every response in the thread, so it may have been covered, but where I think spellcasting (in general) falls down is that there is usually a zero opportunity cost to using that particular "main" ability:
Fighter/Barbarian/Ranger - attack (main ability) - roll d20 = success/fail
Thief - sneak, backstab, pick lock, stealth - roll d20 = success/fail
Cleric fighting - roll d20 = success/fail
Wizard/Spellcaster of all types = cast spell = automatic success.
Now, that being said, there are usually "spell attack rolls" for some spells, saves for no/half damage for some spells, etc. But there are others that just always work - utility spells and rituals mostly.
I'd be fine with a wizard having access to "all the spells" if there was a d20 roll to successfully cast. Whether that was an "attack roll" type d20, or a set DC based on level of spell, or some set DC based on wizard level, etc. That way, the wizard is playing in the same ballpark as the rest of the "main" abilities of other classes. Its not a given. Yeah, it would suck if the wizard's Web spell fizzled in the above example, but likely no worse than when the fighter rolls to hit and misses. Or the thief blows his stealth roll, or whatever.
Some of the other options proposed above - less spells, harder access, spell learning, etc. all sound good to me - and that is coming from someone who IS a wizard player. It would definitely make me re-think my role, re-think how I use the class in actual play, and wouldn't be so "rinse, repeat". My last wizard I played had the most damaging spells prepared, a smattering of utility (cause, you know, everyone had darkvision, we had heroes' feast and other rations covered, etc.), so those mattered less than pure damage and control. It became pretty much 'by the numbers'. The only hitch was the save of the monster, and in those cases, I prepared multiple spells to target different abilities. The monster usually had one really bad save. And it only needed one failed save to be rendered out of action when the rest of the party piled on.