There's quite a bit of content in the 1-5 range that has you fighting non-coporial enemies. I personally found this extremely annoying when I was a newb. Ghosttouch was all well and good(took me all of 2 seconds to figure out that it existed and what it did), but as a prefix it was very annoying as it meant I couldn't have a nice damage prefix.

So moving ghost touch into a suffix was a very useful improvement... for the first 5 levels or so. By then you're past easily 80% of the ghosts and its really no longer a problem.