Designers showed a lot of light washed denim for spring. I think it's more suitable for summer paired with the sheer fabrics, florals and all the romance.
Alexander Wang showed denim with denim, which I would not like unless it's done in a light color. It somehow looked right. Christopher Kane kept things raw with a cropped denim jacket and some see through. Karen Walker's denim dress is a bit darker than the other two and a safer choice.
I don't think this trend will get overly popular, but with these young and talented designers, which collections have been praised, it's certainly going to be tried. We've already seen a few celebs wear it, like Sophia Bush, who stepped out in light wide leg jeans. It is a hard look since it's not as slimming as darker shades, but definitely more interesting for those sunny days.