The original drive for going 'bleedless' on the 787 was for fuel efficiency - some people at Boeing became convinced that if you got rid of service bleed, the engine design could be optimized much better - enough to easily compensate for the massive weight of the needed power generation and electrically driven air cycle machines. Addressing engine related fume events did not play a significant role in the decision.
The improved fuel efficiency didn't play out - turns out that any improvements in engine cycle efficiency was minimal - to the point where the high pressure compressor is common between the bleedless GEnx-1B (787) and the conventional bleed GEnx-2B (747-8). The GEnx-1B simply incorporates blanking plates over the service bleed ports.
That's why you don't see bleedless engines on the 777X or the 737 MAX - it simply is not worth the trouble.
BTW, there has been a least one 'oil fume' event on the 787 - caused by a malfunction of the air cycle unit (which uses the same lube oil as the engines). So getting rid of engine bleed air is not some magic cure for oil fume events.