In certain cases device size where filesystem is created is not know in advance, and it's impractical to try guess correct inode ratio to satisfy filesystem limitations (which is 4G inodes for ext4 and ldiskfs).
We need a flag to tell mke2fs to limit inode count to match current filesystem limits.
Example of current behavior:

# mke2fs  -i 1024 img
mke2fs 1.42.13.x2 (29-Sep-2016)
mke2fs: too many inodes (5269225472), raise inode ratio?
root@kvkvm1oem(0):~#

Proposed behavior (example only, feel free to change message text):

# mke2fs  -i 1024 --adjust-inode-count img
mke2fs 1.42.13.x2 (29-Sep-2016)
mke2fs: too many inodes (5269225472), changing to <supported FS limit> 
... formatting continues ...