I don't think they should be explained UNLESS someone asks, and ALWAYS try to avoid the udercurrents... the thing is , IS the undercurrent really there, (in your example I agree, seems to be self agrandizing pseudo intellectual bable for it's own sake, but it is hard to understand "tones" and motivation when reading peoples posts or an authors explanation.. either way I think it only hurts the interpretation if YOU let it.. I have read the bible many times over and have many people (many of whom are very knowledgeable about the subject) have given varied interpretatons, and (granted the author himself only directly intervenes in the spirit) I have never felt less about a previous interpretation because of an expanded later interpretation.. it just makes me realize MORE about interprative symbolism.. and about MYSELF ....and hopefully about the author...

As to the WHY of explaining, I personally think it comes from a NEED to be accepted by a group , a need to connect. it's as basal a need for a social animal as is food, water, and air.. so sometimes it's just about the authors need. (just my opinion of course..) to me it is very much the same as the questions, "Why does one wirte a lyric "in plainspoken language" and TRY to connect with the audience.. Especially lyrics that contain a moral lesson, or a "higher message" granted the explanation is contained within the lyric, but the need for connection would seem to be the motivator to at least SOME degree.