You're wearing rose-tinted glasses. The ****** TPS design of that era is un-fondly remembered for two cancerous ideas: cover-based shooting that was so exciting and dynamic, it made Duck Hunt look like Quake; and the "gritty" and "realistic" color palettes that best resembled the Ganges during a cowdung-worship festival.
Here is, no joke, the first screenshot I found from Gears of War 3, which came out that same year and was a best-seller that the gayming journos wouldn't stop fellating:
SM1 wasn't a masterpiece or anything, and turret level is deffo a trope that looks silly nowadays. But it was well received as a breath of fresh air, because your roided-out superman (a) was charging and 'zerking instead of cowering behind a chest-high wall and taking potshots like a pussy, and (b) wore glorious smurf blue and gold and slaughtered green orks and purple daemons, instead of everything being smeared in desert brown so American teens could get psyopped into dying for Israel in the middle-east.