After graduating with a Computer Science — Digital Media degree, my first job was actually titled UX Developer — and that was 5 years ago! I truly did spend about half my time programming and half my time doing design work.
While it was fine for a time, I, and the organization reached a tipping point — if I was going to grow beyond a mid-level job and if they were going to grow, I really needed to start choosing a side, and I went with deepening my design skills. (Also I was tired of learning new programming languages and design seemed to have more timeless skills).
That being said — I am absolutely a better designer because I spent enough time actually understanding the medium I was designing for. I just don’t think it’s a long-term position if you or the company is going to grow.