Well, I'm not the first to say this but it deserves emphasizing.
Ideally, schools are to wizards as domains are to clerics. I would be very happy with narrower schools, and I think there's some evidence for that in the article (fire and radiance; thunder and force; cold and acid; lightning and force). If creating a magical tradition is just a matter of picking two or three "arcane domains" to specialize in, and your implements are particularly potent in these domains, it would work very well.
The fluff is appropriate as long as it is given the proper context in the PH. We would not complain about flavor text in the 3E PH which said:
"For example, clerics of Wee Jas delve into the mysteries of death and the dark sources of arcane magic."
as long as it appeared after an explanation that domains are small groups of spells, that clerics get to choose two, and that gods grant their clerics access to a short list.
I really hope the analogy holds. How about a PH that says:
"Wizards may design their own arcane tradition by choosing two schools to specialize in, or use one the sample traditions given in this chapter. A school is defined as a short list of themed spells associated with one of the wizard's implements."
Would that be so bad?
And on a side note, since acids seem to be liquid by default, freezing acid makes some sense. Imagine the spell Acid Shard, which drives an icicle into your flesh. As it melts, the victim takes further damage each round.