I'm largely agnostic, but it's completely untrue that you can't figure out combat effectiveness of different weapons without xp messages. You have access to your raw xp. If you can't use that to figure out how well your weapons are working to generate xp...that doesn't say positive things about you.
I agree with Muod that more numbers ruin the illusion. So, while it's not a big deal to me, I'd probably vote against the messages. I'd also vote against the levels of mobs being displayed. That's very ugly-ifying to the atmosphere. Descriptions (long and short) should be trying to paint a word picture, and "behind-the-scenes numbers" spoil that.