slows down typing
I too intially couldn't figure out why Poles would use the "cowboy" (US) keybaord rather than their own. As it was explaiend to me, it was not a matter of preference but availabiltiy. The first comptuers were składaki, assembled by small fly-by-night firms from usually cheap Made in Asia parts catering to the huge US market where the US keyboard prevailed. Poels got used to it and don't mind double-typing for Polish letters. Most don't even know there's an alternative.
That does not change the fact that Polish 214 is ideal for both Polsih and English plus a few other languages thrown in. Not only is faster typing possible but it is far more convenient and versatile, becuase everything is right up front on the keyboard. You don't double-type to type Polish diacritics: ą, ć, ę, ł, ń, ó, ś, ś, ź and ż. Neither do you have to go into the INSERT mode of the toolbar to type garçon, façade as well as déjà vu, Übermensch, mañana, Višehrad and others with no hassle.
But the clusmy, time-consuming and non-versatile Polish double-type Programmer's Keyboard rules the roost. Poles are a docile lot and readily take what they get. If more Poles had demanded the Polish 214, it would have become widely available. Incidentally, even postage-stamp-sized countries like Denmark use their own national keyboards, but not Poland!