I'm sure you could, but another USB-C port is certainly more expensive than a barrel plug. How significantly this affects the BOM I can't say, but due to the complexity of USB-C I assume it's not totally negligible.

If you want the port to handle PD, various (display) alt modes, high speed data transfer, maybe even TB, you may need a few additional controllers. OTOH having multiple USB-C ports with varying capabilities can be quite confusing.