Bigger in photography means, faster, better, stronger (and more expensive).
Many people will say the only advantage of a digital SLR is that it gives you the flexibility of interchangeable lenses.
I think that’s bullshit.
If it was true, then the days of the dSLR are surely numbered—EVIL has arrived. EVIL, for those of you who don’t know, is an acronym so new, it doesn’t have a Wikipedia page yet. EVIL stands for “electronic viewfinder, interchangeable lens” and they are a new class of camera I’ll talk about another time. Suffice it to say, EVIL will not replace SLR photography—in the same manner that APS-C has not yet dethroned 35mm (much to my surprise). Besides, a lesser-performing EVIL camera costs nearly twice as much as the kits in this article.
I believe the biggest advantage can be found in its name: Single-Lens Reflex.
In order to have a single-lens design, in order to house a reflex mirror, the dSLR has to be big—and bigger, in this case, means faster, better, stronger (and more expensive).