I think by default current versions of mkfs.ext2/3/4 default to 256 byte inode size (see /etc/mke2fs.conf). This IIRC enables nanosecond timestamps with ext4, and as you say, more extended attributes fit within the inode. Such extended attributes are, for instance, ACL’s, SELinux labels, some Samba specific labels.
Bigger inodes of course waste a little bit of space, and as you make them bigger you get into diminishing returns territory pretty quickly. The default 256 bytes is probably a perfectly good compromise for most situations.