To be useful to me personally as a DM, an NPC statblock needs to reflect the NPC's actual stats. Combat-only statblocks that are a subset (or, in some cases, a superset) of what the NPC is capable of out-of-combat don't do me any good, because it is important to me that how an NPC fits into the setting reflect their capabilities. If I need to determine the out-of-combat capabilities of a printed NPC spellcaster before I can use it, then using the printed NPC doesn't save me any time or effort.
Yes, my insistence on harmonizing NPCs' mechanical abilities with their role in the setting is idiosyncratic. And yes, 5e has always had lots of NPC entries that I find less than useful. But WotC's increasing use of the types of statblocks I find least useful means 5e is drifting away from supporting my playstyle. For what is ostensibly a big tent edition, that's disappointing to me. I'd prefer they find ways for the edition to support a wider range of playstyles over time, and make the tent even bigger, rather than shrinking it.