Didn't see any post on this but I can be pretty freaking oblivious to the obvious. So here it goes anyway. After zoning into Queens Island trade skill instance, I could not zone back out without using /zone. Also zoned into an apartment for the hell of it, and again could not zone out without use of the /zone command.

Aye, the Island tradeskill instances need work (no population, thus no widgets for zoning out) and player housing is about a year from being developed (required zone instancing support). So /zone is your only option in those cases.
Thanks for the report.