Arsenal have been a stable club since the past few years. Within touching distance of winning the PL over the past couple of years.
Sooner or later they're going to win a league title especially with Pep's cycle coming to an end so talking them up like they're a Roma level club is pretty ignorant.
These days, Arsenal are a pretty attractive destination for young, flavour of the month players. And Arteta is slowly shaping up to be one of the top coaches in Europe(similar profile to Motta as well).
Understandable decision from the player if he went to Arsenal.