I found some Unicode bugs in porting—and I get continued free security updates. Seems fair to me, and certainly not “no benefit”. I can keep on 2.7 as long as I like; nobody’s forcing me to port. Compare the situation with Java!
Isn’t that comparable to java? Oracle gives you paid security updates on version 8. You can keep using the previous version without security updates or migrate to OpenJDK 8, which have their own security group. More options, seems better to me.