That's true. Our forum market haven't got affected. During the initial days when bitcoin was accepted by steam our forum helped in getting more popularity, eventually other gaming forums took it to most gamers. Now due to this lot gamers have got to know about bitcoin as well other digital currencies.
Yes, accepting bitcoin will increase their number of customers and sales, like you know many businesses are profit oriented hence whatever that will bring more money to their pockets is what they will be after. Steam without doubts is not an exception here.