Both are businesses. Insanely huge businesses. They are doing what is necessary in business and doing it rather well, as it happens. Shareholders, investors, the stock market - all these and more are dependent to a greater or lesser degree on the successes of these two publishing giants. They have to make money - it's kind of the point aside from making games, of course.
I wouldn't say it's fair to outright call either EA or Activision greedy and uncaring about fans and quality - on the contrary, I think they try to at least attain a decent if not better level of quality in their products even if it doesn't seem much of an improvement over the last title they churned out. The companies contained within EA and Activision do indeed care about fans and ask for their input, from what I can gather, but it's not always possible or even sensible to include what fans want in the next game of whatever.
If fans are willing to pay and play then there is really little point in trying to make out that one or the other is "evil". They are just doing what any sensible business plan would incorporate: generate more profits in order to continue growth, expansion and finances. We live in a world largely preoccupied with the making and spending of money; to call a company greedy for doing the same thing could border on hypocritical unless you do not operate with money yourself.