How do you land 4 cruise missiles in Iran if youre aiming for something in Syria?
If you want to remind the Iranians and several other countries that they are all within striking distance if they make Russia angry. This also seems like the Spanish civil war where Germany and Russia backed different sides to test out a lot of their military hardware. Perhaps Russian missiles are not as good as they would like. At least now they know and can make improvements. Coordinating sea, air, land operations, good practice. Mistakes will be made.