I totally agree with the OP with one caveat. There should never be a reward for completing a Scenario that we can’t get through regular gameplay. For example, if a custom trait was the reward, it shouldn’t be a new one that is Scenario-exclusive. I never want to feel like I’m going through the motions to get something and wasting my free time playing in a style I’m told to. The idea of this turns me off from playing at all.
I am not interested in Scenarios whatsoever and I wish the team had put those development resources into existing systems instead (aspirations, traits, preferences, WHIMS, expanding holiday and club activities, improving gallery filters). Nobody would have missed this new feature if it had never been created, but plenty of us have been asking for other things that need improvement.