@mantisspider
You forget that when the Amiga was created, ISA was limited to a max speed of 8Mhz and the majority of implimentations were 8-bit only. Then, combine in the fact that ISA is little endian while the Amiga was big endian, the fact that ISA is really little more than a modularized 8088 local bus and the Amiga lacks an 8088 CPU, and that at that time the #1 expantion bus was the S-100 from the Apple II, there was no need nor desire for ISA expantion. The primary reason ISA existed in the A2000 at all was for the 8088 Bridgeboard which gave an A2000 the ability to run IBM compatible software. The A1000's sidecar did much the same thing.
Technologically, the Zorro bus was more flexible, faster, and was more widely used (since Zorro was a modified 68k local bus, and the majority of peripheral components were 68k-based, there were a wider selection of potential expantion components than one would have found with ISA) so there was no incentive to cripple the design with a hobbled 8-bit bus.
As for PCI, didn't exist then. However, when PCI was unveiled in the summer of '93, Commodore had plans to switch to it for the next-generation "Acutiator" architecture.
