Reasons for NOT having a separate /boot partition
Not having a separate /boot partition is less hassle. It is the default for all Linux distributions and is suitable for most systems and home use. Use a separate partition only you have a very good reason to, for a specific need.
Reasons for having a separate /boot partition
Not mentioning historical reasons that are typically no longer valid today.
Use a separate /boot partition if:
* the boot loader cannot read the root filesystem, because of encryption, esoteric filesystems not supported by GRUB, etc.
