Since men —hetero and otherwise— control most media, health, and fashion companies at the lofty corporate and creative levels, we certainly play a role in sexualization… hell, we play a role in everything, when it comes to that.
But I hesitate to concede the “increasing, over” modifiers you’ve applied. Having lived through a depressing number of decades, I don’t see the problematic stuff being more pervasive than it was in, say, 1988 or 1999.
The big difference I see is that women are now more actively involved in their own sexualization than at any time in human history. A couple generations of twentysomething girls have seized the means of production —cameras, keyboards, and their bodies— and have been busily bending the whole thing to their will.
In fact, in that context, Tumblr’s retreat from nudity has been more than a bummer… it’s something of a tragedy that has undermined a revolution which focused on a woman’s sexual intentions as much as her tits. For an all-too-brief time, this place served as a lab for the exploration of female sexuality and a demonstration of all the ways men make that exploration unnecessarily difficult.