Poppler and poppler-data are now hard dependencies.
PDF is a common-enough format nowadays that import support is likely
considered as a granted feature by everyone. Moreover the current
fallback to the PostScript plug-in for PDF support just gives a degraded
experience with less features (and probably a lot of bugs since
basically nobody uses this code).
Poppler-data is also considered mandatory because non-western language
support should never be considered an "option". People using non-western
languages are not second class citizens and therefore if we say that PDF
import is now a hard feature, it should also include PDF using CJK or
Cyrillic languages.