My 2 cents..
Marketing between 87-90 was a big reason the Amiga failed. Commodore should have gotten the Amiga into the large electronics chains like Best Buy. I know they had the A500 in Sears, but the A2000/A2500 and A3000 (the professional models) could have used the exposure. I think those machines would have done well sitting next to Turbo XT's and 286's.
The Amiga dealer situation was also pretty crappy here in the states. In Minnesota, the only place you could get an A2000/A3000 was at a commodore dealer. The dealers here did not offer a level of professionalism that could be found in the PC market. I remember one "dealer" who literally had his store in a garage and the store was called Protecto. Why would I buy a $1500 machine from a company called Protecto that was located in a garage? Of course at the Commodore dealer, you didn't have a PC sitting next to it as a comparison. The best selling point for any Amiga would have been having it setup next to a PC.