3D graphics formats are essentially data-driven, like a vector-based SVG, but optimized for 3D rendering. (vertices and faces, instead of points and curves and color information) If you wanted to do real-time rendering using something comparable to vectors, you would just use 3D, even if your camera was set up for orthographic projection. The biggest loss would be the lack of a smooth curves option. If your art style doesn't require a bunch of very smooth curves, definitely go for it.
Vector's biggest advantage is that they scale so well. If you do a 3D-fueled vector substitute, you can opt to render at low resolution with anti-aliasing turned off to replicate a low-res pixel art look, or scale up to high definition with anti aliasing turned on, and go for a cleaner, more modern look. If you are fine with pre-baked graphics the same can be accomplished using standard vector art by simply rendering it twice. One low-res version with no AA for the retro pixel look, and one high-res with AA for the clean, modern look.