The XD platforms popularity has been both surprising and universal. I think the reason for this stems from the trigger.
Glock's took off in the 80's w/LEO's, most of whom at the time were armed with DA revolvers so Glock's heavier trigger was not a drawback to these folks and many non LEO's believe that if Cops are using something, it must be the best.
This did not wash with deciples of John Browing like myself who grew up behind the "still number 1" SA trigger set up of the 1911.
The XD, while definitely a striker gun like the Glock, put's the firing pin spring under 100% tension when the slide is racked where the Glock only puts its spring under 60% tension.
The result is of course a lighter, crisper trigger that everyone appreciates and that finally gave us 1911 guys a hi cap poly we could live with.
Throw the improved ergonomics into that bag, offer it in .45 ACP, and you've got a winner!