If it’s any consolation, pretty sure I said the same thing to insta when trying to improve ln-symmetry, for pretty much the same reason. My irc logs confirm: <_aj_> meh, that probably doesn't work, 2022-10-22 
If you’re revealing the settlement tx hash via the annex, then that has to be included in the annex of any update tx, whether it spends the funding tx or a previous update tx. Otherwise, you wouldn’t be able to be sure you can spend that update tx to the latest update tx.
(If you restrict your protocol to 2-party channels, you can change the protocol to only be “A spends funding tx to update N; B spends update N to update N+K; A cannot spend update N+K to N+K+L”, in which case you could skip the annex in B’s spend)