The reason English speakers were satisfied with using
he in the past is not always because it was assumed men alone were important, any more than words like
mankind were meant to exclude women. (I sometimes find myself using
humankind.)
As
Graves and Hodge liked to point out, English grammar is a complex hybrid of several languages and is often arbitrary and inconsistent on the structural level. Simplifications and workarounds were tacked on later, just as programmers sometimes try to make overly elaborate code less cumbersome with workarounds instead of rewriting it from scratch.
One can never write perfect English in the sense one can Spanish, Italian and French. That grid doesn't exist in English, which is why usage and logic are especially important to clear expression.
One of the workarounds has always been synecdoche -- in this case, the use of a specific class to refer to the more general class. Thus, "let he who is without sin cast the first stone" is meant to imply
he or she, with
he actually taking the first seat in terms of pseudo-taxonomy.
Even if the practice wasn't understood to favor men until now, modern speakers hear a level of coded discrimination. The problem is that a neutral gendered pronoun has yet to be introduced or accepted.
In the 70s and 80s, certain feminist writers simply reversed the pronouns to read
she and he; in the '90s, with typographical fun available to all, we saw the use of
s/he in critical and experimental writing. One problem with that practice was that it excluded the forms
him and
her and the possessives
his and
hers. If you continued with the logic of
s/he, you'd end up with unreadable formulations like
h/e/i/r/m.
The current practice is to use the plural forms
they,
them and
their, but the sound of subject-verb disagreement always makes me wince. Implementation becomes yet another annoying exception, another contextual ambiguity, to be memorized and excepted by those who must write and speak presentably.
The problem is that any forms we introduce now are going to sound weird and unacceptable to most people for at least twenty years, and the attempt to create neutral forms would become politicized rapidly, if only because cultural issues which are abstract are the easiest for opportunists and reactionaries to exploit.
My vote would be for three neutral forms which could either incorporate letters from both gendered forms or avoid them entirely by creating an entirely different derivation -- perhaps going back to the beginning of English to explore other choices. I'd love see what a group of linguists might come up with.
An example of gender combinations:
hir (for
her or
him),
hes (for
hers or
his) and
hse (for
she and
he).
Easy to invent, but nearly impossible to standardize.
* * * *
Some would argue that trying to remove sexism from the structure of any kind of grammar is a pointless exercise unless you create a new language from the old. Their chief example of this might be someone's attempt to remove gendered articles from French.
* * * *
To respond to a few earlier suggestions:
Thou and other such archaisms aren't pertinent because they are previous forms of the second person pronoun
you. The specific problem in English is third person singular:
he,
she and
it.
Other doesn't work (or matter) for the same reason.