The problem with character arcs, though, and it has happened time and again, is that it's like burning your way through a candle. After you move through the character arc all the way, the character no longer has any reason to exist. Whatever you wanted to "say" through the character has been said, and the show gets stale. So keeping characters in developmental stasis may seem artificial, but it also extends the franchise.
In Trek, we saw this play out with the TOS movies. They had to give Kirk TWO storylines where he was wrestling with aging, TMP and a do-over with TWOK. After the crew settle in with the Enterprise-A they really have no "arc" left to them, which was a big reason why Trek V was a stinker. When it came time to write Trek V, much of the character-based storytelling of the crew (in arc mode) had already been used up. That's when you get "Row, row, row your boat" and Scotty bumping his head. It falls into farce.
So when you embrace arcs, you also have to embrace endings, which franchise owners don't like because it kills their cash-machine. And often-times these endings are unsatisfying (death of Kirk in Generations was, and the ending of Nemesis was also very anti-climactic).
This is true across the board. Look at what's happening to Big Bang Theory. Sitcoms never used to have arcs. Now they do, for the novelty aspect and because everyone else is doing it. And it's great when you're in the middle but as you get towards the end the entire thing starts to feel played out as all of the character movement you setup at series start has already taken place. That's fine in the context of a 90 minute movie--to have a final act or scene to tie everything up. But to have the arc stretched over 9-10 seasons means the last season or two of episodes will have all the characters (simultaneously) at their happily-ever-after state of maturity and inner-peace. This causes problems trying to continue to manufacture conflict as the current episode demands it.