At the time the Abrams was designed people were worried about 10,000 Warsaw Pact Tanks pouring over the Inter-German Border. It's design was perfectly understandable and reasonable.
The Abrams was designed to stop Soviet Tanks at the Fulda Gap. There was never a thought to making it an urban fighting platform.
It's superb at killing enemy vehicles at long range. Its utility as an urban platform remains to be seen. From the reports I've seen, it's not doing all that well.
Hence the need for a 'retrofit' as it's politely called.
L