Why is this a bad thing? There's already self-balancing involved - by diverting points from a primary stat, you become slightly weaker offensively in exchange for defensiveness and enhanced survivability.
And, of course, player choice in breaking the usual stereotypes.
You also never wind up with stupidity like how items in the same set in DA2 were scattered across four different level requirements (say, 6, 7, 9, 11) meaning by the time you got to equip the entire set, it would be bordering on obsolete.
As to your last point, yes - I disliked finding the different set pieces all over the place, some in boxes or chests that you may not have noticed, and spread across 5+ Levels, I certainly hope that won't be making a comeback. A poor design choice.
And to the first point - Without fatigue, it offers no downsides for the person doing it, because they'll still be using all of their abilities at the same energy requirement; not that I'm one to turn down a free upside. But a Rogue in full plate being able to backflip, stealth and cover huge distances - all with the stamina of a Racing Horse on Speed? I'm going to say that's a poor choice in and of itself.
Not to mention, they did have attribute runes or Armor runes to offset it for a lower class. I typically used a mix of the two runes on my Mages to make them a bit more hardy for combat, or overclocked my Rogues on Damage and various runes that aided that so I just disintegrated anything that I came across.
And I'm all for breaking class "Stereotypes", some of my favorite playthroughs were Arcane Warriors - or Dual Axe Rogues (using The Veshialle if you managed to get it 2 times from Bodahn.), but a lot of the time, it lead to hard lessons of "I hope you've got a save from before you boned yourself." - Like taking Blood Mage early in DA:O, Or Reaver on a Low Constitution Warrior.
"Over Simplification" you can call it, I prefer to call it "User Friendly".