When your 1GB hard drive is full, you don't buy 1.1 GB hard drive, you buy 2GB or 3GB hard drive
When your 1Ghz CPU is too slow, you don't buy 1.1Ghz CPU, you buy 2-3Ghz CPU
 (of course recent years CPU upgrade only gives you about 20% increase in performance so I have not upgraded for years, therefore the block size bump can be dangerous without sigop limitation )
When your 1MBps Network is too slow, you don't buy 1.1Mbps, you increase to 10Mbps

Any upgrade less than 2x is a maintenance release