If the bulk of attributes are based on bonuses from equipment then it's not really out of player control at all. It's just not a permanent choice, but one that can and will vary depending on the how the player decides to equip their party members, in addition to the Passive Abilities they choose which many provide permanent increases to certain attributes, though they seem negligible compared to what the equipment can provide since it's only a few attribute points compared to tens of them. It does remove the chance of players permanently breaking a build since all you have to do is change armors or weapons, but that's not really a bad thing.
If it's robust enough you can likely easily try out different builds like a high Dex warrior. Though whether or not the attributes are actually designed to be useful across all classes remains to be seen.
Even if true, having Heavy armor that supplies the STR to wear it seems less effective than having the STR inherently on the PC. One might lose armor, or have it stolen, confiscated, etc. Even worse would be to be reliant on devices for Magic or Willpower, as the loss of said device would seemingly make a Mage quite vulnerable.
Again, I like the idea of more item customization, but am not a fan of losing the Player's control of the character build to get it.