If I remember correctly it was some 'clever' Microsoft hacking that was the problem. 24bit of address space should be enough and the top 8bit of addresses (e.g. pointers in C speak) were used for other purposes.
It's way more likely the fault of the compiler used to write the code... although if that was an MS tool, you would still be right. Just not intentionally so.
IIRC, Amiga Basic was dropped in WB 3.0, but was shipped with the A500+ and A600. I am not too sure about that, but it should work on those machines.
Could be wrong about that, but I do remember thinking "Why isn't this included anymore?" and never getting a straight answer from anybody. If it plain didn't work on an A1200, that would explain why it wasn't included with the computer anymore.
EDIT: Yep, wrong, ABasic was dropped in favour of Arexx, which CBM acquired from IBM. Never included with the A500+ or A600 either.
https://en.wikipedia.org/wiki/AmigaBASIC
