I'm definitely jazzed about the game. Probably the game I most want to see right now!
I wouldn't worry about missiles. Sure, they have their place, but they are also pretty random weapon (the number of missiles actually hitting varies and there's no aiming them). Having them and kiting is an option for a 'Mech that's fast, but they aren't going to have that much ammo.
Shooting legs off and then killing you when you can't do anything is more likely going to be the order of the day, if anything.
That is depending a little on how aiming works (I'm assuming it's basic FPS stuff here, ie. point, click and hit). In the boardgame, shooting legs doesn't predominate because target location are random. Well, except with Targeting Computers (which are Clan Tech anyway), but even then the Called Shot penalty is sizable. However, Clanners with big ER PPCs shooting your legs off is nasty business (a Light 'Mech will lose their leg in one or two shots), but it doesn't dominate gameplay (because those types of 'Mechs are rare and expensive) in the boardgame, but those tactics very well might in-game. That said, hitting legs isn't the easiest affair necessarily.
But boooooyah I wanna get in this game!!