Weight saving isn't the only advantage

1. Efficiency is always the maximum attainable with chain drive, approximately 98%
2. Simplicity, very little to go wrong
3. Ease of maintenance and cleaning
4. Robustness, the likelihood of breaking a correctly installed chain in good condition is almost zero
5. Same experience day and night, just get on and pedal, no trying to work out what gear you're in on a pitch black rural lane
6. Improved fitness, and better 'core' strength and condition
7. Cheaper to maintain, unless you're an NJS junkie
Maybe others will add to the list......