The advantage of upgrading from the Technician to General class is not only additional bands that you can operate on, but also an increase in power. While Techs are limited to 200 watts on HF, Generals can transmit with up to 1,500 watts PEP on the HF bands. That’s a lot of power!
The biggest incentive for upgrading from Tech to General is the increased HF privileges. Generals can transmit on two new longwave bands that are below the AM broadcast band, as well as 10 HF bands that allow worldwide communications in a variety of modes. Many hams who go for the General class license do so because they want those HF privileges.
If you are interested in providing emergency communications, having access to most HF bands almost is a necessity so that you can pass or receive traffic depending on the propagation at various times on each band. General class licensees have access to all amateur bands, just not every amateur HF frequency. During disaster situations, amateur HF communications get through without failure.
Also, Winlink is an HF-based email system that can be used nearly anywhere in the world. Winlink is just another good reason to get your General license if you are interested in being able to provide a service through your ham station or you have a need to send messages from remote places.