As for his limits, I would suggest two possibilities. First, and most obviously, his purpose is to serve for only short term situations in the absence of the ship's doctor. Now, such instances can come in the form of brief, but intense, periods of activity during a crisis, such as the Doc was thrust into in Caretaker. Alternately, it might be for a somewhat extended period during which there is very little activity, or the threat of such, but the EMH would just need to be available until a distant star base was reached , for example.
Another rationale might have been Starfleet having some incipient concerns about the capabilities of this first of its kind, functioning medical practitioner to be stationed on starships. Without casting any aspersions on the skills of Dr. Zimmerman, there might have been a current of thought not to enable the full range of subroutines, that without the validation first of successful flight experience, might, aside from being largely superfluous, prove to be too taxing for the hologram to process successfully while still keeping his focus on his overwhelmingly primary task. A variant of this might have been that some troubling advance reports on the EMH's personality for instance, might have been leaked to Starfleet Command, instigating some retrenchment in programming, perhaps lowering the bar for a rollout that would be deemed satisfactory.
One other obstacle that might have been needed to be overcome, could've been the the simple recalcitrance of some members of the Command Staff, for whom this use of technology might have seemed too premature or unorthodox. Might there not have been other admirals who, like Paris, did not seem inclined to invest much serious time, effort, or attention to the variety of holographic applications anyway, so could've been naturally more cautious and wary of this use of the science in this manner.
Another rationale might have been Starfleet having some incipient concerns about the capabilities of this first of its kind, functioning medical practitioner to be stationed on starships. Without casting any aspersions on the skills of Dr. Zimmerman, there might have been a current of thought not to enable the full range of subroutines, that without the validation first of successful flight experience, might, aside from being largely superfluous, prove to be too taxing for the hologram to process successfully while still keeping his focus on his overwhelmingly primary task. A variant of this might have been that some troubling advance reports on the EMH's personality for instance, might have been leaked to Starfleet Command, instigating some retrenchment in programming, perhaps lowering the bar for a rollout that would be deemed satisfactory.
One other obstacle that might have been needed to be overcome, could've been the the simple recalcitrance of some members of the Command Staff, for whom this use of technology might have seemed too premature or unorthodox. Might there not have been other admirals who, like Paris, did not seem inclined to invest much serious time, effort, or attention to the variety of holographic applications anyway, so could've been naturally more cautious and wary of this use of the science in this manner.