I understand why level 12 is the max level. Regardless, I lose all motivation when I know my major growth path no longer exists.
(...)
Am the minority opinion?
I am sure you are not - there a games entirely revolving around filling XP bars and making stats go up. I have seen a similar complain popping up in other cRPGs as well.
I don't think it is that kind of game though. I see leveling in cRPGs like that mainly as a way of defining your character - an element of become stronger is definitely there, but I don't think it is meant to be a primary drive. Rewarding players with XP is a form of incentive, but it is not the only reason to do quest - story, characters, roleplaying, item acquisition etc. If filling xp bar is your main driving focus I can understand how it can be demotivation, but I think one also needs to acknowledge that there is far more than the game offers beyond that.
Personally, my ideal RPG is one where I reach max level with a some end game content left - I do want to play around my a maxed out character. From what I understand BG3 does just that. With a fairly completionists playthrough I think I am around level 10 or 11 early into act3. I think level pacing, has been actually done rather well.