I remember someone saying "There was no market for 'Amiga games', there was a market for Amiga 500 games." If you look at it that way, it had a nice long run as a game machine, while failing in most other segments.
That makes total sense. The A500 was the most popular machine, with a 68000, 512K RAM. If your game required 1 meg, you'd lose a decent number of potential customers. (My A500, circa 1989, was souped up! 3 megs of RAM and a hard drive!)
Meanwhile, there was a market for high-end PC games. If you bought a better PC, you could show it off. That was important to the type of person who owned an Amiga (they always wanted to show you).