While vector images have many advantages, they also have shortcomings.
Vector data is, in general, better suited for items which have hard edges. Vector graphics do not excel at creating soft edges areas or shapes which blend into other soft-edged shapes.
Yes, you can use raster effects in many graphics applications to blur or "undefine" the edges of something. However, doing this ultimately creates embedded raster images. Within many vector apps raster interpolation and scaling is not something which happens or if it does, it doesn't happen with excellent results.
While software has advanced a great deal, there are really many things which can not effectively be accomplished in vector images. While it is true you can "trace" most raster images to convert them to vector, many of these tracing are less than optimal if the subject matter in one which contains things like blurry or soft focus areas.
Subject matter is a huge factor. If an image already has hard edges then there's no reason to not use a vector version. But soft-focus raster images will never trace well. Realize for logos, drawings, etc. vector data may be perfect. However, for portraits, hazy landscapes, etc. vector data would be insufficient.
Ultimately it all comes down to desired appearance. If you're fine tracing everything and ultimately losing soft focus edges in photographs, then more power to you. However, almost every tracing carries with it a clear indicator that the image is not smooth across the board. I defy you to show me a tracing of a soft-focus raster image which exactly mimics its original. There's always some give and take.
Think of the difference between a GIF and a JPG - there are simply some things which don't work well in the GIF format. Same holds true for vector images -- there are simply some things which do not work well and it makes little sense to force an image into an undesirable format when the end results won't ever be equal to the original.
I love vectors and use them as much as possible. But I also know you can't throw out the baby with the bathwater. Raster images have their advantages and will most likely never fully be abandoned.