I enjoyed this post from Idle Cartulary on their blog, and I feel like the vibe is kinda one that would fit here, essentially 'there's design preferences and having them doesn't make you morally wrong'.
Can't count the number of times that I've bumped into people who've been convinced that There Is One Correct Way to play, which is really funny to me. Anyway, I thought it was a neat way to say 'people are going to want different things from different games', which I really wholeheartedly agree with, and wish more people would talk about with their groups. I swear this is why many groups end up fighting - because they're not clear about what they're expecting to get out of the game or the style of the game before they start playing, and when that tension is revealed later, it causes arguments.
I don't know if I agree with the assertion that there's no such thing as bad design, but my disagreement is more nitpicky than anything so can probably be ignored - I'd call it bad design if your DM book says 'this book will help the DM run games!' and then is layed out or written in such a way as to obscure that goal. I see that as 'game design' as much as 'this is the way that you make characters' but I think that's just a difference in term definitions more than it is a disagreement on fundamentals. Is 5e designed badly if combat takes forever? Nope, especially not if you're one of the people who enjoys it.
I think that is also a matter of preference.
I mostly GM very open, player driven campaigns, but a while back I ran the Dragonlance campaign. I used 4e instead of AD&D and changed some things, but stuck to the major story beats. It was what most people would call a "railroad". I wouldn't say it was entirely free from player choices and consequences, but it was more about choosing what equipment to use and making tactical decisions in combat, rather than choices dictating the course of the campaign. We had fun! Unfortunately, the campaign eventually went on an indefinite hiatus, because the amount of prep work I had to do was just too much.
Now I run a Traveller campaign for the same players. It's a sandbox, entirely different from the Dragonlance campaign. The players travel around the subsector and do whatever they want. I personally prefer this kind of campaign, because what happens in each session is a surprise to me, and it's not as prep-intensive. But my players seem to enjoy both styles. They're having fun in the Traveller campaign, but occasionally reminisce about the Dragonlance campaign and ask if we're going to pick that up again someday, because they want to know "how the story would go".
I don't think there is anything wrong with either style of campaign, as long as everyone involved are enjoying themselves.
I think this is exactly it! The point of any game is to have fun. The details of how you achieve that don't really matter. As long as you and your players are happy you can free roaming the sandbox or chugging along the railroad tracks, or anything in between.