Doesn't all AmigaOS3 software run under EUAE?
More or less yes. But usability also depends on how heavy the game is. Remember, there is no JIT available for EUAE. A game demanding a 060 and AGA could be a bit too heavy for many EUAE setups.
And if you are a bit inteested in MorphOS still, with a cheap PowerMac G4 or eMac the option to play around with it is good now. Some ppl were lucky to pick up PowerMacs or eMacs for virtually no cash or even for free.