That C= persisted with OCS and ECS for so long has some positive benefits, the A500 had a very long and stable commercial life compared with other platforms.
AGA was a mistake, being too little too late, most A500 owners (ie the commerially viable userbase) didnt make the jump to AGA machines and got left behind. The A500's poor upgradability didnt help. AGA machine pricing and value take some blame too.
C= couldve managed the transition from O/ECS to AGA better by focussing all their resources on the problem, advertising, consolidating product lines and trimming the fat, maybe?
But it was late in the day, and the Amiga had already lost face as a serious computer at a time when people started wanting serious (work) computers to do home accounts, word processing and not just play games.