Keeping a separate home partition lets you keep your files should you reinstall your linux distro.
GRUB doesn't support ext4, so if you're going to use that filesystem for the rest of your files, you'll need a separate boot partition. GRUB doesn't supportnow supports ext4, so if you're going to use that filesystem for the rest of your files, you'll needkeeping a separate boot partition, while still an option, is no longer necessary.