I would like to get rid of the default sample rates we have defined, because IMHO it can be confusing. Currently, we have the following default values:

replaysSessionSampleRate: 0.1, 
replaysOnErrorSampleRate: 1

While these values are good defaults, the problem with defaults is that it is "magic" - e.g. if I set this config:

Sentry.init({
  replaysOnErrorSampleRate: 1
})

it is IMHO not clear that we will still capture "regular" replays 10% of the time. The same way vice versa, with the current setup replays will by default ALWAYS be captured, meaning each and every user will have the impact of replay running, even if I configure e.g.:

Sentry.init({
  replaysSessionSampleRate: 0.1
})

due to the error sample rate being 100% by default.
We also don't have this for other rates, so I'd propose to default them to 0. And just make sure in all docs to always provide both values as defaults to copy-paste.