So your main question is that you have everything on your site ranging from blogs, photos, videos etc and yet your users are inactive.
I'll list few facts here and you are sure to get your answer:

1: Time is limited and people do not have entire day to use social networks. Had you been in place of your users, would you engage yourself in a third party website? I dont believe that if I give you some link of a dolphin website, you'll shun your activity over facebook and enjoy that site. If you see more WOULD NOT, your users WILL NOT.
So at first, you'll need to make your website so much interesting that you yourself engage in revamping and improving it more than any of your users.

2: Secondly, you do not have to put the whole pile of modules in order to make your site more interesting. Remember: whatever you install is only going to make things complicated for the user to understand and another speedy alternative (facebook) is already at their disposal. So the users have enough of time to migrate away from your network and reside in the big communities.

3: Lastly, I think apart from the technical grounds, the interest and the USP matters more. If today, even if you make a search engine better than google, do you think you would be able to overcome its reach? Probably not (not so easily atleast). So you need to have something of the same feel but a different reason being given to users to try. Like for eg: Google was always better, but Justdial offers a localised search tool and many features better than google.
Remember: Following the same trends is not the way. You cannot beat the giants in their own game. Better is to find your niche and expand your reach to influence more and more people on a daily basis.
I'd also like to recommend the website maintenance pack listed here: www.yoonixmedia.com
Maybe you can give it a try.

regards
mike