I kinda feel like this was done on purpose, but... since there's no mention of it in the changelog it might as well be a mistake.
Anyway, ability to disable it most certainly didn't hurt anyone and for some of us it is preferrable to play without locking belts to straight lines.
"Lock belt building toi straigh line" setting is gone
Re: "Lock belt building toi straigh line" setting is gone
Is there a option to bring that back? Sometimes it's really painful that you can't put line of belts vertically, for measurements or whatever...
Edit: Nevermind... saw discord discussion. Shame it was removed, I know it's due to programming issues. But still, it's a thing that restrict player somehow out of his freedom of building however he wants.