Some games rely on specific BIOS calls to boot. Using the original files ensures the game "thinks" it is running on a real console. 2. The Boot Animation
Ethically, this respects copyright: the user dumps their own copy for personal use, never distributing it. Legally, under DMCA anti-circumvention provisions (Section 1201), the act of dumping may be gray if it requires bypassing a boot ROM lock, but most jurisdictions permit backup copies of firmware for interoperability (emulation). ds bios7.bin file
To really "look" into the file, a Hex Editor isn't enough. You need an ARM disassembler (like Ghidra, IDA Pro, or the dedicated arm7dis tool). Some games rely on specific BIOS calls to boot