I think I2C and SPI have very different use cases. Over I2C, you can interact with 127 devices with just 2 pins. To do the same with SPI, you'd need 130 (4 + an additional CS for every device on the bus).
You may think of the extra pins as not a problem, but on every product I've worked on we've been pin-limited on the MCU.
You may think of the extra pins as not a problem, but on every product I've worked on we've been pin-limited on the MCU.