I don't really care how it fits into "real world" standards, though I don't really believe Starfleet personnel practices as presented would actually work as presented. But I don't think it was a good way to go for a major character.
They tried to have their cake and eat it too with Riker, presenting him as a dynamic and active leader and at the same time a subordinate content in his place. In TOS, they had the five year mission, so you could assume that assignments and transfers were somewhat frozen for that duration. You can also imagine Spock or Scotty preferring to advance in the scientific and technical fields rather than go for vessel command. Riker, though, was always presented as a command officer through-and-through, born of the early concept of Riker handling the action and Picard overseeing. As presented, the highly capable Riker character would seem to want -- and indeed deserve -- his own command as soon as possible.
Considering the realities of keeping a TV cast together, things could have been written so Riker was still too junior to get his own ship, or even to avoid the subject completely. Instead, they serve it up on a platter to Riker in Season 2. And not only do they make him the offer, but they give Picard a pretty good speech on why he should take it. So the whole Riker character after that point can be questioned: Is he command material or a second fiddle? Is he ambitious or cautious? Does he want to be challenged or to be comfortable? Is he confident or unsure of his abilities? And then they do the same thing again with Melbourne.
There are a couple of other internal inconsistencies on the issue: One, Picard says Ares is an "insignificant" ship, but on a possibly important exploration mission. If Trek has showed us anything, it's that routine exploration can quite suddenly become tricky, dangerous and "significant." No vessel on independent exploration would seem to be an unimportant job for a captain. Two, it's made pretty clear in "Chain of Command" that Starfleet orders changes of command of its vessels, so that raises the question of why Riker wasn't just ordered to a new command, or if he was, why he was allowed to refuse the order.