It's because it's not a Super Speed Stage. All boss stages that force the player to control Sonic manually in order to chase a boss are, to quote you, "just wierd". Sonic Adventure 2 was actually the first game to feature this type of boss fight, and it was featured in later titles like Sonic Heroes, Sonic Generations, and Sonic Forces.
I'm more of a Super Speed Boss stan than a Boss Rush stan, personally. It just makes Quick Stepping more natural somehow, which is both ironic and hypocritical because Super Speed Stages (post-Unleashed specifically) are designed to align Sonic in 1 spot at a time while running automatically.
Ikr it's shown as a normal stage but then turns into a boss, and it's the only boss in the game that has red star rings, number rings and silver moon rings, and the boss isn't too hard but it's kinda there
You're thinking of the Death Egg Robot boss fight. This fight uses the same concept used in the Shadow Rival Boss fight in Sonic Generations: the player is forced to run manually rather than automatically on an infinite straight line and defeat the given boss before the timer reaches 0:00.000.