I've been meaning to submit this passage to this sub for some time now. I think it gets to the heart of the meaning of women only space and why certain people get so testerical about it. Everyone should go read the whole essay here:

"Male parasitism means that males must have access to women; it is the Patriarchal Imperative. But feminist no-saying is more than a substantial removal (redirection, reallocation) of goods and services because Access is one of the faces of Power. Female denial of male access to females substantially cuts off a flow of benefits, but it has also the form and full portent of assumption of power.

Differences of power are always manifested in asymmetrical access. The President of the United States has access to almost everybody for almost anything he might want of them, and almost nobody has access to him. The super-rich have access to almost everybody; almost nobody has access to them. The resources of the employee are available to the boss as the resources of the boss are not to the employee. The parent has unconditional access to the child’s room; the child does not have similar access to the parent’s room. Students adjust to professors’ office hours; professors do not adjust to students’ conference hours. The child is required not to lie; the parent is free to close out the child with lies at her discretion. The slave is unconditionally accessible to the master. Total power is unconditional access; total powerlessness is being unconditionally accessible. The creation and manipulation of power is constituted of the manipulation and control of access.

All-woman groups, meetings, projects seem to be great things for causing controversy and confrontation. Many women are offended by them; many are afraid to be the one to announce the exclusion of men; it is seen as a device whose use needs much elaborate justification. I think this is because conscious and deliberate exclusion of men by women, from anything, is blatant insubordination, and generates in women fear of punishment and reprisal (fear which is often well-justified). Our own timidity and desire to avoid confrontations generally keep us from doing very much in the way of all-woman groups and meetings. But when we do, we invariably run into the male champion who challenges our right to do it. Only a small minority of men go crazy when an event is advertised to be for women only-just one man tried to crash our women-only Rape Speak-Out, and only a few hid under the auditorium seats to try to spy on a women-only meeting at a NOW convention in Philadelphia. But these few are onto something their less rabid compatriots are missing. The woman-only meeting is a fundamental challenge to the structure of’ power. It is always the privilege of the master to enter the slave’s hut. The slave who decides to exclude the master from her hut is declaring herself not a slave. The exclusion of men from the meeting not only deprives them of certain benefits (which they might survive without); it is a controlling of access, hence an assumption of power. It is not only mean, it is arrogant."