We can reason subjectively from the perspectives of Mozilla/Google, or we can reason objectively from the perspective of people.

The concern from people is always about too much power (control) in the hands of a select few.

What choices will they make?

Will they be the best choices?

How will we know?

How much transparency will there be?

Some of these might not apply directly to the open source world, but Google is at the forefront of decisions on the internet.