Agreed. Although I obviously do hope more and more 3rd party developers will start developing for AFS2 I also really do hope those addons will (also) released through Steam. Last week I wanted to reinstall P3D 4.2 but after two tries I decided to forget about it for now because of 1. all the work involved and 2. various incompatibilities (and 3. developers blaming each other for those incompatibilities). I absolutely LOVE how AFS2 is constantly up to date without having to worry about incompatibilities. In that regard it is great that IPACS likes to do as much as possible themselves. I also bought LOWI through Steam and regret getting KEGE form Orbx themselves. (Helgoland I am not interested in btw: way too small for my taste.)
I certainly hear you about wishing I could have bought it on Steam, but I wanted to show Aerosoft that FS 2 has a vigorous user base that is willing to open up their wallets. As far as size goes, it isn't huge by any means, but as Jetjockey10 says, you get more than just the islands. In fact the Islands are a small part of the package. The area on the mainland is probably over 10 times bigger. Maybe 100 times bigger lol. But you should certainly hold off until you are convinced it suits your needs!