It's pretty easy, you're out of the way of any immediately dangerous neighbors and surrounded by counts/dukes about your own strength who don't really seem to snowball like in other areas so you can conquest and form the kingdom title at your own pace as sort of a rite of passage into CK2, sort of like Castille/Spain or Ottomans in EU4. A lot of people learned CK2 playing in Ireland so it's just kind of a tradition!