It's impossible to find data about PC userbase and total software, but if we look at the best selling console games in each gen, and the best selling PC games in the same timeframe, consoles always win so this isn't too far fetched.

So, what reasons do you think are behind this?

convenience is the number one reason. 

Lolwut? League of Legends has 30Mil active users, Diablo 3 sold around 8-10 Mil, wth are you talking about?

"Historically". I'm not talking about now only.

And a few Wii games beat LoL, and a lot of them Diablo III.

couch gaming

Like not enough space in the room or something else?

There's a lot fewer people with gaming quality computers for technical and cost reasons.

At the end of the day, Joe-schmoe would rather pay $200-300 bucks for a console to plug into the TV and not bother with the technical details of building and maintaining a high spec PC.

Have you SEEN the average person's computer/laptop? It's a crawling nightmare of viruses, spyware, crapware, adware, icons, and just an overall mess.

I know, but Wii Sports (Resort) shouldn't count :P

MKWii - I'll give you the point.

Diablo 3 still sold better than most games on consoles. I just wanted to show that the situation on PC isn't as bad as your OP implies^^

plug and play.

however consoles this gen and more so next are going away from that (i.e install, patches), hence we seen PC gaming increase in recent years.

Bundled games doesn't count but free games do? I think that's unfair :P