(1) Attributes
As I mentioned, attributes have been traditionally used as a fundament for other aspects of character customization. In early tabletop RPGs, they determined what class you could play, and later, they were chosen in order to benefit a specific class. Either way, they were an important way to make our characters unique. Even in games as late as DAO, they influenced what you could learn in many different ways.
In DAI, they do not have that role anymore. Basically, attributes are irrelevant except as they influence combat. In that, we may now even be more variable than before, because attributes are now more influenced by equipment and we can change equipment to create different configurations. Since learning of skills does not depend on attributes any more, this results in an overall increase in the degrees of freedom when playing the game. However, equipment is not a part of our characters, and now that all variables are external to the character and all characters remain unrestricted by individual attribute allocation with regard to what abilities they may learn, this results in a net loss of ways to make our characters unique.
I find it hard to evaluate if these things have ever really been that important in the past (speaking only of DA games), or if this was an illusion and my choices were so much determined by my class that this new system just canonizes what people did anyway, except for minor variations. I don't know how this will feel in the actual game, but it feels different from here and requires a significant mental switch to adapt to from the old mindset of "attributes are the fundamentals of your character". Also, that customization options are moved from character to equipment creates an unfortunate vibe of "what you have is more important than who you are".
In my humble opinion Ieldra, attributes have never been true character customisation in Dragon Age at all. Not a single one of them marks any form of significant change in how your character can interact with the world. The only true impact they had was lock away certain abilities from you and have an obfuscated impact on your damage/defense. This essentially made the attributes in DAO a pacing mechanic, an extension of the level systems.
Would you truly have noticed if the abilities and equipment were locked away only by level rather than both level and attribute in DAO?
The only attributes that was tangibly reflected in the world itself in a enabling manner was cunning and strength, in their effect on persuasion checks. But even then it was the skill, not the attribute, that did the heavy lifting.
For anything else you'd need a spreadsheet to notice the difference (apart from, as I said, it's function as a pacing mechanic). Putting points in high strength did not allow you to use that to overcome obstacles. High magic did not grant your character a closer connection or understanding of magic. Constitution did not allow your character to run for longer. What was average scores? What was considered strong? Gifted?
This is what essentially makes it what I would call false character customization, in that it has a purely mechanical effect. Whereas hair colour, which abilities/skills you picked, what equipment you wore are examples of true character customization in that they all have tangible effects in what you see or can do.
Whether you had 34 or 38 in strength was not tangible, whether you could talk down Ser Cauthrien was. The difference between 12 or 17 dex was invisible but whether your characters hair were red and black was something that was reflected. The attributes were even more abstract than hitpoints, and that's not saying a little.
Now, what we lost was the ability to make a less than perfect character. I can see this being a rather significant loss in terms of defining your own character. It was a freedom we had and could be very rewarding. Unfortunantely, such builds are also traps easily fallen into by new players. Which makes it a feature that might be appriciated by experienced players but alienate new ones. Sabotaging your own character is only fun if you do so intentionally after all.
Losing control of the attribute system also makes has an effect in the immersion of the development of your character as you could gauge your character slowly developing themselves. But I'd argue that the ability system serves the same role, though reflecting more the learning and mastery of techniques rather than purely increasing muscle mass (or equalient).
So, I'd argue that we haven't lost much in terms of character customization at all. What we had before in terms of character build has simply moved to other parts of the build. Fewer questions are asked, but we're not left with less choice. And if the non-combat use of abilities holds what it promises, we may in fact have gained in terms of customization in this part of the game.
That's not saying that attributes shouldn't have a tangible non-mechanical impact. I'd like that too. But it's not something DA has really had in any significant degree thus far. That's not something we've lost, it's something we've never had.