I have always been loyal to the brand when it comes to servicing etc, I prefer a grease monkey who knows the car better that one that thinks he knows the car.
yes servicing can be done anywhere, but if something needed to be fixed under warranty then you would need an abarth garage, which for me would be hassle in having to book the car in twice.
as Sandys said, I also did my research and knew what I was getting into when I bought the car, I had asked about servicing etc and was fully aware.
I would also think as more Abarth garages/service centres pop up the price will start to get more competitive, but also you have to bear in mind, rising raw materials and labour over 3 years has gone up.