My take is that people would probably feel less "That's it?" if the Second Scenario ending wasn't so damn easy to come across. It's the most conclusive ending next to S.F. but it's so easy to get it as your first (or one of your first) endings because it's gotten to by general goody-two-shoes moral decisions and backing up your friends and being suspicious of Sirei, something the average moralfag will get to, or get really close to on their first try.

Then that just leaves you with 99 other endings that are nothingburgers, aren't nearly as conclusive, or take the plot in a completely different character-driven direction because the plot's mostly been solved.

If the Second Scenario ending was harder to stumble across somehow because it made you do terrible or morally questionable things more often it'd take longer for most people to find it and people would have a less averse reaction to just grinding out a bunch of subpar endings. It's the first, or one of the first endings people find.