[dooq]

Em is probably the very simplest guitar chord to play, only needing 2 fingers beside each other. Yet it doesn't come in at the top of the list. So I don't think your explanation is the dominant force here.

[kevincennis]

No way. Em7add11 is waaaayyy easier if you use the right voicing.

[dfan]

Yeah, if you went by novice guitar player easiness, the keys of G and D would be at the top, not C.

Also, barre chords enable you to play in any key you want, so it's not like playing in C# is particularly harder than playing in C.

[te_platt]

Except that C is a (the?) natural third cord to use with G and D. And then it's a bit tricky to not get something that sounds like a John Denver song.