If I wanted social contact, I'd (a) start or attend meetups, and (b) work out of a coffee shop or the library. I wouldn't pay a $100-$150/mo(!) premium for it.
$200/mo sounds like a decent price for this, though, especially if I wasn't super-committed to my company.
I would find this valuable if I was self employed. I'm the type of person who currently has the choice to work from home or the office every day, and 95% of the time I choose the office.
I'm not advocating avoiding like-minded people; that would be silly. I'm saying there are ways to get that benefit without shelling out cash for it, and, for that matter, the control and stability that comes from having a 6mo or 1yr lease instead of a month-to-month arrangement.
If it's so hard for you to get the networking and cross-pollination you need that you have to pay $150/mo(!) to get it, I have bad news about how hard it is to acquire customers, partners, and investors.
An office is as bleak as you make it.
One thing that bothers me about coworking spaces is the "anti-office" mentality that assumes the world would be a better place without any kind of working privacy.
The amount of serendipity & opportunity that comes out of coworking - when the coworking community is run properly - is incredible.
I moved to Philadelphia from Vienna, Austria for the community at a coworking location (http://indyhall.org). It's not because I lacked for bodies.