I took both of them at face value that they just were busy or unneeded at the time. Captain Marvel has the excuse of being galaxies away and Fury knew this. Your friend tells you to only call them in an emergency, you don't call them because you drank the last of their milk while house-sitting. Fury knew she was busy and was assembling his own team to fill in because of this. Also, we may still get the Dr Strange reaching out to Fury scene to warn him, so even when things get bad in, say, Ultron, Fury knows that he needs to save the pager call for a bigger Hail Mary.
For WW, I took it as her not being called or needed between times. She decided to lay low and learn more about humanity, and she isn't omniscient. She doesn't have the resources of Batman or a deep network of spies to report every little thing in the world, so she just does what is within her sphere of influence. Think like a Marvel Defender, who has a 'territory' in NY they defend, unless something draws them out into the larger conflict. She was hiding before Batman found her out and made the connection.
If you think too hard then any construct will fall apart, and for me this is where the suspension of disbelief comes into play. We cannot have something be 100% true to life with EVERYTHING making sense, so we need to allow our disbelief to be suspended. And for a game, who is the star? You are in the role of the specific character. So the focus is on you. Other heroes could be taking breaks, addressing other issues, or just plain unaware that it is happening until after the fact.
The important thing for me is the enjoyment of the ride at hand, so long as at least a reasonable effort is made to suspend my disbelief.