2. Any Android users with iPhone friends trying to use iMessage for group chat cares about it. It's impossible to add Android users to an existing group chat... and any time you have a mixed iPhone + Android group chat it degrades a number of the iMessage group chat features normally accessible to iPhone users.
3. Any Android users receiving media over SMS/MMS from an iPhone user cares. They'll be receiving images & videos that look like they were shot with a potato.
The blue vs green color doesn't matter, but the effects mixed platform chatting has on both iPhone & Android users is significant.