I'm optimistic that 2018 will be a better year for Destiny 2's player experience. I've come to accept that it's the norm now that the first several months (maybe even the first year) are always going to be awkward for GaaS titles as they grow into their communities. I feel like the same was true for The Division, Destiny 1, and so on.
The biggest thing I want to change this year is Bungie's style of messaging. The Division's "State of the Game" streams gave players much more insight into fixes, incoming features/content, and so on. I'd love to see the same from Bungie's CommDev team. I want to see less of individual developers communicating tweaks or soliciting feedback on sites like twitter. CommDev folks should formalize a stream or section on TWAB's blog posts for developers and manage the message, and the community's expectations, that way.
Finally, I really feel that a PTS wouldn't hurt either! I've grown tired of events being canceled or sullied by things that should have been fixed before that content went live. (Mayhem was awful because of Novabomb spam but the holiday break meant a fix was impossible.)