There's no such thing as a bugfree "big" game really. There's just too many variables to account for. Even today, more than a decade after release games like WoW, FFXI, CSS have a list of 'known issues' that slowly gets pared down and then replenished as patches roll out and old bugs are squashed and new ones are found/created. It's a neverending cycle. In the last two years D3, GW2, FFXIV, Civ V, SWTOR have all dealt with serious bugs, particularly post-launch. The common denominator? Big online multiplayer. It really just comes with the territory imo.
And ultimately I'm still having a blast playing BF4. It crashes and doesn't work perfectly, but to me a fun game with bugs is much better than a boring game with no bugs. It'll get better and I think they have their priorities straight personally.
Plus I don't think you can sue a company for their stock price going down. You could maybe make a case for their product not meeting expectations which caused a price decrease, but ultimately I don't think being unhappy with your investments is going to hold up in court.