Linux programs are difficult to port and they use X Windows for the GUI stuff and that has to be re-written for AmigaOS using Reaction or MUI or whatever GUI you choose. Not an easy task.
Not necessarily - Holger Kruse wrote
AmiWin X11 which is x-windows for amiga.
I thought the problem was that amiga has no GTK toolkit (etc). Kronos? You know more about this sort of thing :-)
