Realistically, the Nokia C2-01 is a 2G/3G phone. In many countries, carriers are shutting down 3G networks (AT&T and T-Mobile in the US killed 3G in 2022; UK and EU follow by 2030). However, in developing markets, the C2-01 is still used as a backup phone, an MP3 player, or by collectors.
Flashing this phone is worth it if:
If you bought a used C2-01 or set a master lock code and forgot it (Nokia default is 12345, but previous owners change it), the only way to reset it is by flashing the phone. A factory reset from the menu doesn't clear a forgotten master code. nokia rm 437 flash file
Why technicians seek the RM-437 flash file: Realistically, the Nokia C2-01 is a 2G/3G phone