This is a fascinating discussion, but is getting a little beyond the scope of this forum. Is there a place to argue about historical trends, etc.?
I agree that there may be characteristics of a conlang that would require (or, at least, make highly advantageous) the use of a nonstandard script (6 voiceless sibilants, for example), but the language must then have something extraordinary to justify the added effort to learn it. Perhaps also, if it were learned as a spoken language first, so that the need for the distinctions were clear, the strange notation would be acceptable. But, in general, such creations are rare (I am reading about a language for termites and one for birds and also ones for various other non humanoid types elsewhere, but they stand out exactly because they are uncommon).
As for the historical discussion, enough to say that I don't really see your comments as objections to mine, beyond some quibbles about words.