Well actually guitars have been extremely popular instruments in modern music since the 50s. It's nothing very new. Keyboards do play a big part in modern music. But now they are used for so many other sounds nowadays eg. brass, strings, pads etc it is just not as obvious that a keyboard is being used unless it is a piano, organ or a synthesizer sound.

The band I play in plays classic rock and has 2 keyboards and 2 guitars so the score is even.