Why I do have to install an addon, which restores something, what IMO everyone on this thread and probably most people out there would love having as native? Na

Why I do have to install an addon, which restores something, what IMO everyone on this thread and probably most people out there would love having as native? Namely not flat-design visually easy to parse tabs! Any occurence of flat-design stuff on software, which is used day by day, was and is awkward, because it causes displeasure and it is more time- and eye-consuming.