Ok, then, how should i imagine a single thing about my character if he is just a list of predetermined perks? Also, perks don't make sense. For example, i put all my starting points on strength (if attributes are still in, that is) and then at lvl 40 or so i think "Well, i choose that perk that lets me carry 50 more weight", so all 39 levels before i can only carry 100 weight-units, and suddenly, without my character changing, just because he puts a label on himself (like "Pack Rat") he can suddenly carry more?
He isn't a list of predetermined perks. The perks your character gets can be different from someone else's, and there's hopefully plenty to go around. Also, if attributes are still in, I don't expect things like encumbrance to remain static.
But we don't know everything of how the perk system is going to work, nor do we even know what all the skills will be. What we do know is that there are perk levels, so you'll have to level up a perk to make it more effective. It's kind of like extra skills, except less granular levelling and tied to a base skill (unlike previous games where each skill was a completely separate 1-to-100 scale). We can also hope that you can only pick perks related to skills that you levelled to achieve your current levelup. In that way, encumbrance could work similar.. your encumbrance limit in Oblivion/Morrowind only went up because you decided to stack more points on strength, not because of anything your character actually did. Encumbrance-enhancer perks can be tied to strength-related skills and be selected the same way.. just without the exploiting to get x5 strength modifiers all the time.