I think we get to blame the subjunctive on Old English speakers and writers.
In English Syntax: From Word to Discourse, Lynn Berk has this opinion:
Like the term imperative, the term subjunctive refers to a particular verb form. In Old English, special verb forms existed to communicate non-facts, e.g., wants, hopes, and hypothetical situations. The subjunctive is somewhat weak in Modern English, but there are speakers who use it routinely. In many cases, the subjunctive is a form learned in school or through reading, so it is educated speakers who use it most.
I’m guilty of aping the subjunctive from reading "too many" old books.
On the other hand, as far back as the 1920s, Henry Fowler didn’t think much of its use:
About the subjunctive, so delimited, the important general facts are: (1) that is is moribund except in a few easily specified uses; (2) that, owing to the capricious influence of the much analysed classical upon the less studied native moods, it probably never would have been possible to draw up a satisfactory table of the English subjunctive uses; (3) that assuredly no-one will ever find it possible or worth while now that the subjunctive is dying; (4) that subjunctives met with today, outside the few truly living uses, are either deliberate revivals by poets for legitimate enough archaic effect, or antiquated survivals as in pretentious journalism, infecting their context with dullness, or new arrivals possible only in an age to which the grammar of the subjunctive is not natural but artificial (A Dictionary of Modern English Usage).