After we upgraded from 4.1 to 4.2.1, they re-worked the like button to do just what you're suggesting, but that is not supported in the current version of the skin, so instead of showing the default icon, which would look out of place, it shows nothing instead. If you insist on liking posts, you can change back to the default skin with a drop-down menu at the bottom of the page.
We will need to upgrade the skin eventually. But the right person needs to do it, otherwise whoever downloads the update will have to pay the $30 required a second time, to get the upgrade.
TLDR
The like option is still here, but not displayed when using the FISD/Engraved skin.