But plate armor wasn't heavy and it was articulated. It was flexible and allowed a great range of motion, actually. Neither was a greatsword heavy, only around 4-6lbs, give or take. You're not going to get more tired because you sway when walking, unless you have two dwarves strapped to your hips.
Most two-handed swords are in the 2-3 pound area, even. Games have an unfortunate way of assigning far too high a weight to weaponry in general. Of course, with the rather over-sized swords that people in Dragon Age tend to end up with, it could be more in the 6 pound range... but yes, either way, definitely not heavy enough to be a burden.
Anyway--on topic, I am not sure a toggle would be as good as having an option in CC, like with Saints Row 2, that offered a full range of walking animations.
That would be best. I think a toggle would probably be more realistic, at least in the immediate future (it could possibly be either patched or modded in, whereas a full range of animations couldn't be).
No burly macho man animations slapped onto a small female frame (Mass Effect) and no extreme swimsuit runway model strut, just look at a large group of real people to get an idea. People complained about the DA2 Lady Hawke strut (though I saw it as a bit more fitting in DA2 than DA:I) and BioWare not only didn't make a toggle, but used the same animations for DA:I. 
Honestly, I thought that the animations in Mass Effect were fine. I hardly even noticed them. Of course, I am small, and I do walk and run in what I suppose could be considered a more 'macho' way (at least compared to DA II/DA:I), so it probably just looked normal to me and perhaps not to other people.
I agree that the strut made more sense in DA II, since it did fit with the only voice available. Those two things combined to make me uninterested in playing a female character in that game, but at least it was consistent.
If BioWare wants to give us the option of choosing our walk, I'd rather it be in the character creator like Saints Row, rather than a toggle.
I believe that is what people are asking for, in fact -- an option in the character creator. If it is a choice between two things, that basically does make it a toggle.