I've already mentioned elsewhere that I fucking love Cernunnos Woods "Awaken the Empire of Dark Wood" from the CMI sublabel Cruel Moon. Even more primitive than Mortiis, but also lacking the slightly comical aspect.
When I revisit other CMI stuff, I find that I really enjoy most of what I used to enjoy back then. Come to think of it, I'm obviously not sure I even agree with the premise of this thread. Since I took until now to realize that, I will list a few releases anyway.
M.Z. 412 - In Nomine Dei Nostri Satanas Luciferi Excelsi (Not a very cool theme, but good music - dark, sometimes a bit harsher, always interesting).
Aghast - Hexerei Im Zwielicht Der Finsternis (This I actually like better than I did when it was released - back then I found it a bit annoying for some unclear reason. Misogyny, no doubt)
Deutsch Nepal - ¡Comprendido!... Time Stop! ...And World Ending (The points made in the original post have some relevance for this album, but I still think it rocks)
Any Proiekt Hat, even after all that's been said most Mortiis too... And of course the In the Shadow of Death compilation 7". Lots of it, really. To me, the stuff that "doesn't hold up" never really did.