leave
them
open
It seems like such a simple answer to such a heated topic.
It's not as simple as you make it out to be. Ignoring it does not make it go away. Why would a good-aligned character even have a "Go help Molag Bal" quest in their log? Why should such a good-aligned character not try to do everything possible to bring closure to it? This in addition to being a usability nightmare, cluttering the quest log with tasks you're completely uninterested in completing and cluttering your inventory with quest items you can't drop.
The game railroads you because it makes you finish a quest in a specific way, even if you've been actively trying to sabotage it. Tell Molag Bal to f-off, tell the Priest of Boethia what Bal was planning, go and make sure he doesn't get himself killed... oh, you want to see the priest dead, right? okay, now go do what you've been actively working against.
How is that not railroading? It ignores the entire reason you did what you did, forcing you to a specific end despite doing everything possible to turn away from that end. It completely lacks giving you the option to do what your character would do.
Another example is Jaree-Ra, in Solitude. He offers you a not-so-legal job. Your choices are to say yes, or threaten to turn him over to the guards. If you threaten him, he just brushes it off and you're not able to actually tell the guards, while he waits for you to change your mind. Again, railroading as the only way you can finish the quest is by doing it a specific way, and not being given reasonable options that your character would do.
The kicker is that some of these quests are already failable, such as the Molag Bal quest. However, to fail it you have to resort to murder, which instantly locks out the option for any good-aligned characters. So you have a quest where the only way to fail it is to be a murderer, and trying to do the "right thing" locks you into becoming a murderer. There's no reason a good-aligned character couldn't also fail the quest by refusing Bal's command.
Skyrim: where no means yes.