@nikitonsky My read on this is that they are asking for permission for things that most other products just do invisibly in the background, without asking. The fact that it's even possible to use Helium without it connecting to any servers ever (!) other than what you type in the address bar makes it different than other web browsers.
For example, how would they do software updates without connecting to a server?
@nikitonsky In terms of trusting the extension contents, correct that you are now required to trust two entities instead of one. The difference is that Google (presumably) does not know anything about who is downloading the extensions; it seems to me that this is the problem they were trying to solve.
I'm not sure exactly what your concern is, though. The browser maker might tamper with an extension? They made the entire browser, which you're already running. They could do anything.