Rome Flight returns to PHL

Had the scenario played out at LH's Munich or Frankfurt hub the pax would likely have not even noticed.
that's likely true. especially since they have more than enough widebodies to cover things like this.
They fly the most direct route, also accounting for prevailing winds. Typically, that does go up over Greenland, South of Iceland and into Northern UK. Just look at a round globe and it becomes apparent how much shorter it is to do that route, versus just going directly East/NE over the Atlantic. They also need to have landing sites that fit the ETOPS requirements.

The company attempts to file the flight for the most efficient track, which may or may not be the most direct one. The tracks are drawn up each day and assigned by Oceanic Control, who will attempt to grant the requested track, traffic permitting.

Eastbounders from PHL will normally stay south of Greenland, and never get close to Iceland. While the flights to Northern Europe will commonly coast in over or near the UK, that would not be the case for the Southern Europe flights. The FCO flights in particuliar would typically come ashore over France.

The issue of ETOPS divert fields is rarely an incentive for a more northern route for several reasons. First is the presence of several possible alternates in the Azores (due west of Spain), which also enjoy a superior climate to Iceland. It should also be noted that US Airways does not use Greenland airports as ETOPS alternates.

The second reason is that US Airways has 180 minute ETOPS authority, which in simplest terms means that one alternate can be in North America and the other in Europe, with none in between. This may sound a bit scary but is in fact the norm for major US and European airlines crossing the pond. It is also a baseline requirement for CONUS-Hawaii ops because of a lack of existing enroute alternates. Happily, the America West flight department was eventually granted this authority (with some timely help from their friends at US Airways Flight Ops and Maintenance) after repeated embarrassing turn downs from the FAA.

As a general rule, the eastbound flights to Europe are attempting to take advantage of strong prevailing tailwinds, and the westbounders to avoid strong headwinds. Thus, the morning tracks, which are drawn with westbound flights in mind, vary greatly from those in the evening. Northern Europe to Philly flights are frequently far enough north to pass over Greenland on their trips home.