Ben had an interesting post at M* about the Old Testament. I've mentioned before that I love the Old Testament for many of the same reasons that Ben lists, but I also agree that many members of the Church aren't very comfortable with the OT.
There are obvious reasons for this. We talk about the symbolism of Isaiah and the difficulties we might encounter there, but we rarely mention similar difficulties throughout the OT. We focus on Isaiah because of the emphasis Nephi placed on Isaiah, but there is still work to be done with other books of the OT. It is also important to remember that some books of the OT (like Ezekiel and Daniel) could not have been on the Brass Plates since they were written after Lehi left Jerusalem, so Nephi's not mentioning them does not necessarily make them of less value.
The OT is very different from any other book of scripture. It is quite the hodgepodge of different things- genealogy, poetry, prophecies, children's stories, allegories, lots of history, etc. I imagine that Mormon was working with a collection of texts that was somewhat similar to the OT when he edited the Book of Mormon. One person's going through the entire OT and editing and possibly adding some other ancient texts would make for an "easier" OT- not that I'm advocating that.
All these things contribute to people's reluctance to reading the OT. Still, I think the primary reason we ignore it is that the OT is not emphasized in our Church the way the Book of Mormon is or the Gospels. Our focus on the Book of Mormon is good, but I wish it didn't exclude the Bible, especially the OT.