The Enterprise-D, being a giant showpiece ship had the most bleeding edge holodeck of the era. The holodeck uniquely incorporated a lot of TOS advanced alien technology, which Starfleet engineers mostly understood. Mostly. There were some hiccups.

The tech was refined and only in-house developed and vetted holotech was issued out following incidents such as Moriarty. It takes a lot longer to research and create from scratch than it does to plug in some alien tech or coding that you think you understand.

The EMH was not a janitor or menial laborer. It was a highly skilled holographic entity that was repurposed below its abilities. The repurposing was not a decision made to make use of the EMH’s abilities but out of spite by a jaded creator.

Also, whenever you notice something like that, a Q did it.