I've seen this subject come up a lot, and people are always incredibly fierce (or vicious) when it comes to defending their preferred medium.
Before I continue, let me first say that my preference does not equate to a disdain of digital art. Amazing art - as in, the pieces that are truly memorable or inspiring or make you pause to take everything in - are amazing because of the artist, not the medium used. These kind of pieces don't just look good, they present imagery or emotions that are unique in some way to their creator.
So, why do I prefer traditional art? I've actually thought about it a lot, and I believe it boils down to two main reasons.
1. More often than not, I find traditional art to be more impressive. I do NOT think digital art is easy, but I do think it is easier. There's no "undo" button with traditional art, and depending on the medium used, mistakes can't always be corrected. Also, the opportunity to modify in retrospect is often more difficult (if not impossible); no deciding in the last minute that red hair will look better than black, or that the background you painted would be more fitting with clouds rather than flowers, etc.
2. This is the bigger reason. To me, traditional art has a personal touch, a particular connection, that digital art does not. It's like receiving a hand written letter versus an email; there's something about the former that makes it more distinctive. Perhaps, it's that you can hold it in your hands. Or, that what's on the page can never be exactly duplicated by another human hand. This might sound like total BS to some, but I like the sentimentality of it all.
That's about it. I don't have enough active watchers to get much attention to this entry, but I'm happy to have written it. Good food for thought.