Why was Mendelssohn so bad again?

One of the more fascinating memes (did I use that correctly?) in the j-blogosphere (to me at least) is the perennial struggle over the meaning and person of Moses Mendelssohn. If people thought that history had paskened and Orthodoxy conclusively decided he was an oysvorf, that was revealed to be a faulty or incomplete assumption once the world of Jewish blogging was underway. Full disclosure: I am often part of the discussion.

This topic must recur three or four times a year on various blogs over the past 5 years (and earlier on the various Jewish discussion lists). Most recently in this Hirhurim comments thread. Little new ground is broken ("his children converted" "so did other's" "blah blah").

One of the themes which emerges in these discussions is that once it appears conclusively demonstrated that the simple, canonical view is not historically accurate --eg, if he was terrible, why did Rabbi Akiva Eger give an approbation to and order and advance copy of a new edition fully 50 years after he died, while he was already in his 20s when the original scandal and debate over that very Chumash (and by extension, Mendelssohn himself) was raging? In other words, in the same person you had someone who experienced the issue when it was current events, as an adult, and the maturity of experience and age, and the passage of time to reflect on it. It is well known and clear that his colleage and son-in-law the Chasam Sofer took an opposite approach, which means that there are two views in the 1830s, not one-- once that emerges, inevitably some try to show that they have in fact uncovered the heresy in his work, so all the rest is a sideshow.

In 1986-87 this occurred when Rabbi Simon Schwab responded to a proto-blogging discussion which occurred in the pages of the Jewish Observer (and probably in offices and private homes) and noted that Mendelssohn was thoroughly heretical after all. In support he cited some statements in Mendelssohn's translation of the Psalms in which he compared them to secular poetry, or in some other manner regarded the Psalms as literary creations which can be analyzed and criticized as such. This was heresy. (Indeed, Mendelssohn had been reading Lowth. Here would be a good place to mention something about Malbim, but perhaps that should wait for the comments. It should also be borne in mind that his Psalm translation was not aimed exclusively at Jews, thus he had to sidestep modern text critical and christological issues, all while producing a sound, lingsustically and aesthetically pleasing and unheretical translation.) Left unexplained was why it took until 1986 for the evident heresy of a book published in 1770 to be revealed. Not only that, it isn't as if his Psalm translation was unknown to traditional rabbis (eg, R. Zalman Trier subscribed to the 1804 edition) until a German-speaking rabbi opened it up for the first time in 1986. In other words, my contention is that Rabbi Schwab interpreted comments he did not like uncharitably because a historical position required justification after an uproar emerged on the pages of the Jewish Observer.

Today a commenter at Hirhurim relates that s/ he knows what the heresy is. It is that the Bi'ur consistently fails to interpret verses, which some meforshim understand as relating to the Messiah and the World-To-Come, in that light, always accepting alternative explanations by the meforshim. Thus, he could not have accepted the 13th principle of Maimonides. Assuming s/ he is correct, is that the heresy of Mendelssohn? Why did it take until 2010 to discover it? Why didn't the Chasam Sofer explain it?

Am I off base? Truth is, this was a hastily written post meant, hopefully, to provoke some interesting discussion. I can already contradict myself by pointing out that I don't really believe that novelty of interpretation means that it is wrong. Still, I can't understand why these things were overlooked, were they sound and clear reasons why he was and is treif-passul, as opposed to modern meaningful midrash, sort of a yeshivish orange on a seder plate.