That's like saying a pirate should wear a mail suite because he felt it would protect him better against his victims. It just does not make sense for a mage to wear heavy armor unless that is his area of expertise.
The second part of what I said, this makes sense as a reply to. The first part, no. That has nothing to do with the level restrictions on items, which are by far the larger problem.
There are some legitimate reasons for armour restrictions between classes, but I'd much prefer it be done in a way that tells you what those are: for example, not being able to stealth in heavy armour (but still wear it), not being able to cast spells in things other than robes (assuming that's the logic behind mages not wearing armour -- otherwise, I see no reason a battlemage might not decide to wear armour), and armour other than heavy armour just offering less protection.
Weapon restrictions between classes makes much less sense, especially with some of the decisions they made. Bows, for example, make much more sense as a warrior weapon than as a rogue weapon, since bow use requires a good amount of stealth and isn't exactly great for sneaking around in the shadows. Bows for warriors and crossbows for rogues might've made some sense, or throwing knives or some such (it's also kind of annoying that warriors have no ranged capability, at all, and leaves me wondering how exactly my Dalish elf managed to be a hunter when she's apparently incapable of picking up a bow).
This so much. The SPECIAL system was great because you knew what each stat means; 5 Strength is average, 1 is wet noodle, 10 is Hercules level. Clear, concise, meaningful.
Dragon Age's, isn't. What's 40 Strength compared to 30? to 10? To 100? Does your character going from 15 Strength to 90 over the course of the game means he's now 6 times as strong? Apart from arbitrary benchmakrs from armor, it doesn,t actually mean anything.
That is a problem with the system, yes. It always has been. However, that's still the case, it's just that now you're getting almost all of that from your equipment and some from chosen abilities. This doesn't remove that problem.
Clearly defined, not-increasing ability scores are better, in my opinion. So is being able to assign your characters abilities during character creation.
Besides, all allocated stat builds ever do is pigeonhold you into a pattern. Stack one stat, maybe a second one, and you can't go wrong. That's frankly boring and utterly unconsequential to me. I'd rather pick between abilities and passives and whatnot.
That's partly your choice, and partly a problem of not enough points being available to distribute. Take, for example, Baldur's Gate and Icewind Dale versus Icewind Dale II and then versus Neverwinter Knights and Knights of the Old Republic. In the first two games, you're rolling for you stats, and can then redistribute them afterwards. It's entirely possible to come up with a wide variety of different builds. Want a clever, charismatic, but stupid and clumsy fighter? Sure. Want a fighter who's only good at being strong and tough? Also sure, and so forth. With Icewind Dale II there were enough points available that you could still do that, for the most part, although one typically had to sacrifice one stat if one wanted several high ones. In NWN and KotOR, there's no choice, and indeed not enough points available even to make a maximally effective character to begin with.
At this point, not being able to change them, we might as well not even have ability scores. I don't like that, but there it is. If every warrior and every rogue are always only going to have their slight starting boost plus whatever they get from their armour and abilities (which always goes to the same one or two stats), with the rest of the stats flatlined at 10, there's no point in even having them there. Part of the whole point of stats is to show what your character is like, rather they are intelligent or dim, wise or foolish, and so forth. Removing that choice removes the entire point of stats with regards to roleplaying, and does hurt it somewhat with regard to gameplay mechanics as well (although the whole item/ability point thing does mostly make up for it in terms of gameplay, I would still rather have other and more interesting abilities on items and such).