I've never been sure what it is that folks seem to want out of a "story" or "cinematic trailer" for Hawken. I'd hope that the same thing that drew me into Hawken - customizable badass looking mechs with big guns scooting and flying around blowing the crap out of each other - is what draws in others.
What story do you want to tell about it that, in any way, does anything to further explain what you'll be doing?
And, unfortunately, tons of market research and historical data shows that online multiplayer games and single player story games are now almost completely separate entities. People either buy a game because of story mode OR buy a game for it's multiplayer. Many of the biggest games and development studios have switched to doing one or the other for a game. Doing both is also a big financial drain and a huge risk in the time-to-market deadline - the game ends up costing almost twice as much to develop and a delay in either story mode or mp could completely screw a games success into oblivion. If a game doesn't release at the right time, it may miss its window for success and all that money and time spent will completely bankrupt a company.