I agree, Opt in would have been better
Not only in regards to this issue, rather all. Let the customer or user make the physical choice to opt-in, chances are (these days) that most won't.
It's also a more consumer friendly business practice, rather than an half-hearted one. There may be time limits on how long one 'opts-out' or policies can change. Like in the US, opting out of many services are often time limited to 5 years max, not a lifetime choice.
Hopefully Linux Mint simply won't have the Apport choice to make, the team modifies the base Ubuntu distro to reflect their & user's preferences. Often decisions are made based upon feedback during the early beta releases, unlike many others, Clem takes Linux Mint followers seriously over many issues. The more that speaks out against Apport (& many will), the better the chance to be pulled before the final Preview becomes released.