I can only speak as someone from the states so the values might change from country to country. But I personally don't really see a graphical update for Mabinogi being a bad idea at all, we even have PSO2 recently that seems to be doing that and the reception to it so far has been really positive.
The thing about a graphical update for Mabinogi isn't whether it's a good idea or not, but the fact that the engine is so ancient with the team that developed it being long gone, and that Nexon likely would see no reason to overhaul/set aside funds for one of its more niche games. It's much easier to just keep pushing out gacha for whatever money they can make off the game in its current state.
That's very much so true, though the same could be said about PSO2 if they didn't decide to do this whole new update they're putting out. I guess it really just depends on what the company things will be worth it or not, though I guess I'll always be of the opinion that a graphical update is a good idea.