I refresh my profile every 3 months or so and go on probably once a week to check news, contacts and groups.
As much as we may be against social media it is and will continue to grow as a means of communication / research / networking and places such as linked in will thrive as they are the early adopters of this.
Unfortunately there will always be some who refuse to believe this and it will mean that opportunities will pass them buy. Armed forces are a prime example of this, years of service result to not a lot in the big wide world and there are people on here who will testify to this, and how hard it is to get work.
Saying it's for people who love the big themselves up is both puerile and foolish. People are at the end of the day commodities in their most simplistic form. Some are highly trained in useful subjects, others are not, the tipping point is how you market yourself to the biggest demographic of potential employers. To not do this is only to stunt what is possible to achieve.