2 monitors is quite useful for an average consumer. I can play games full screen and do stuff on the other. Or I could have multiple articles up as I type an essay. It's also not that expensive in the grand scheme of computer components at all.
I wouldn't call you an "average consumer".
The average consumer will get along with a stuffty Dell or a second hand Mac.
If you are a gamer with any knowledge of hardware, software, and perhaps computer assembly above your parents knowledge than chances are you are a class up lol.
I'm not so sure about two monitors. I hear they improve productivity a lot, but I wonder how true that is. I get that you could compare documents, or have email open in one monitor, etc. But that only saves the time of navigation. You can't truly "work" on two things at once in all scenarios.