About the A3000 Wikipedia says “The machine is reported to have sold 14,380 units in Germany (including Amiga 3000T sales)”, and about the A4000 “The machine is reported to have sold 11,300 units in Germany”. Both were on sale for about 2 years.
In comparison, the A2000 sold 124,500 units in Germany, again according to Wikipedia, in the about 4 years of its commercial availability.
So, about a 80% decline in sales per month, in what I think/guess was an expanding market for personal computers.
⇒ I don’t think those improvements made much of a difference.
Variants of the A2000 continued in the market after the A3000 was released, such as the A2500, so people who didn't need the upgrades - or could make use of them (e.g. the VideoToaster didn't fit in the A3000 case without modifications) would continue to buy cheaper models.
Commodore's focus on low cost stuff (in their own way) while PC clones managed to push the HDD+SVGA setup price down was a critical factor for how things turned out I think. In the high end there was also Apple, Macintosh had launched a year before the Amiga and made the professional GUI market harder to enter.
But the fateful focus also let the masses have access to a great hacker's computer growing up, without the vibe satirized by "Office Space" that marked the Microsoft platforms.
