Comparing northern Italian food to southern is comparing apples to oranges. They are two different styles. The one that is "best" is a matter of preference. I don't see your logic that, simply because souther Italy is "poorer" than the nothern part, their food isn't as good(?).Sorry, I was NOT referring to South Philly in my post - but indeed someone else here confirmed my observation in some other geography.
I also am speaking as someone who lived in the EU for a long time and so my "Italian" is different from those that had Italian in the US. This is not to say that the Italian food in the US is not better than what it once was but, barring high class NY restaurant (I know nothing of CA and if I am in LA, I would go only to the Japanese Sashimi places), Italian food in the US is unrepresentative, first because historically it was food of the poor immigrants from the South, second because of US fascination with quantity (bigger portion is better and we can see the impact of that all around us) and finally, because it had to adjust to the local taste - the people of English/Scottish stock had only boiled stuff, which I enjoy during my NZ trips at English immigrants' residences, who maintain their own tradition there.
Italian food, whether from North or South is way superior - from a fish baked in oven, submerged inside nothing but sea salt in Genoa, to Orechhiette con cime de rapa in Bari. In the DR, I find better Italian food, a) because the restaurants I frequent are owned by the expat Italians, for example in Boca Chica/SD and b) there is a lot of genuine Italian ingredients available - some of which are not allowed into the US - for example someone mentioned "pancetta".
My favorite restaurant in Cabarete is my favorite, also because and this is fairly rare, that the Chef himself is Italian and not being from the South, has a different culinary footprint. In fact, the original owner of the Bologna restaurant was/is from Bologna and the food used to be excellent before it got sold off. By the way, I find the German and French restaurants around the North Coast to be very good too, again for similar reasons. I mean I found reibekuchen at a beachside place in Sosua - unthinkable!
Good southern Italian food is as good today as it ever was. Unless you're talking about Olive Garden, good Italian food in the US is very representative of that in Sicily and the southern part of the US. I have a feeling that you've never been to a good southern style Italian restaurant.
Southern Italians have always had big meals - way before it became popular in the US. Did you ever have a meal with an Italian family? Ever hear of a seven course Italian dinner?
Speaking of Boca Chica, years ago I went to Italy, Italy and another one that was close by. Both owned and run by expat Italians. I was not impressed. I'm not sure why you think just because an expat Italian owns a restaurant here it is automatically good(?). There are plenty of Italian expat restaurants here and many are not that good. Many are just that - expats. They never ran a restaurant in Italy and their dream was just to retire here and open one.
Some cured meats like pancetta can't be imported, but you'll find far more variety of meats, cheeses, and other Italian ingredients in the US than you will here. Just consider the number of Italians in the US and the popularity of Italian food there.
From what everyone says, Bliss is a very good restaurant, but that's not the type of Italian food I'm looking for. I'll have to try some of the ones mentioned.