These trillion dollar companies were often able to invest into big money-losing moonshot projects that benefited consumers massively - in Google's case, GMail and Google Maps - which were truly unimaginable at the time even though they're taken for granted today, so there's clearly some benefit in the form of innovation. Who else can afford to build things like that?
The questions to ask are, can startups and venture capital take on the role of innovating that these big corps have done? I'm doubtful, since there's been no startup in the past ten years that put out anything nearly as genuinely innovative and helpful as Google Maps was for me, mainly because the risk/profit ratio is so bad without the network effects that these big companies have.
Do the benefits outweigh the costs? Ten years ago, when the big companies were innovating so much to the benefit of consumers, I'd answer unequivocally yes. Now it's much less clear.
And finally, is there any way to rein in the negative effects of these big companies while bringing out the positive effects to the benefit of consumers?