wow, they cut it that much from the manga? guess they figured the original followed it closely enough and nobody wanted to watch that again?
No, it's more that they probably set a goal of getting through the greed arc in roughly 1 season.
Just letting you know, Ed goes to South HQ for his annual assessment (as all state alchemists have).
He bumps into King Bradley who is doing a tour through Southern Amestris at the time, with Major Armstrong assigned as his personal bodyguard.
After talking about what Ed and Al were doing in the south, Bradley decides he wants to meet Ed and Al's alchemy teacher. They go to Izumi's to meet her, the famous Sig and Alex muscles bonding scene occurs, and Ed & Bradley learn about Al's kidnapping by the mysterious homunuculus greed, and how izumi broke her hand during it.
Cue Ed going to fight Greed and Bradley and Armstrong amassing a squad to assist with the rescue of the kidnapped brother of the Full Metal Alchemist.
While Ed is in south HQ, there's quite bit of character development with Greed, Al, and the chimeras. Lengthy discussions about their backstories that all kind of get thrown out here.
The fight between Al and the chimeras is much longer too.