For the time beeing I use the four colour deck.
As a child I learned all the card games like rummy, 66, Mau Mau, and others with the classical two colour deck and this is normal or most common for me.
Old german playing cards have even different signs (acorn, leaves, heart and bells) and they are multicoloured, red (heart) and green (leaves). In southern Germany they play even today with those old cards only.
For me its not a problem, that I have blue and green cards and it is easier to distinct if you have four colours rather than two, especially when the windows is small.