How homogenization is good? Having Wizards that are intellectual in lore and in gameplay, you able to play with a extremely low INT Wizard makes absolute no sense.
There is no homogenization, because each class relies on different attributes to a different degree. While all attributes are important and all classes suffer consequences for dumping any of them, this doesn't mean that every build you make is going to have the same attribute allocation.
Moreover, different classes start with different base values for accuracy and various defenses. This means that the percentile increment provided by each attribute point is class-dependent. In other words, pumping certain attributes is more valuable for certain classes, which, again, works to break homogeneity.
If you play a low intelligence character, you will not be roleplaying an intellectual simply because you will not be passing intelligence checks. Moreover, you will have crippling disadvantages as a low intelligence wizard regardless of your build, because even melee wizards want their summoned lance as well as defensive spells to last longer. For damage dealer and disabler wizards, intelligence plays an even greater role since you want to maximize the efficiency of each spell cast by making sure it hits more targets and lasts longer in the case of disablers.
No, is not. Spell damage is determined by "might" and "might" is only used as STR in game dialogs and checks. So yes, in order to throw hotter fireballs, a Wizard must go to the gym...
Yes, it is. Like I said: any mechanical behavior can be explained by appropriate lore. There is nothing inherently wrong with physical might determining the power of one's spells as long as it's explained by the in-game lore. In PoE, might determines both physical and spiritual strength. Whether you like it or not does not matter:
Might checks deal both with physical abilities and intimidation and intimidation is the ability to instill fear, something that goes beyond mere physical capability or appearance. So no, might is not used merely as the physical equivalent of strength.