Can be. Paying for SaaS offerings like the gsuite or o365 is a great deal for say, 100 seats, instead of paying someone to administer on prem email. "Cloud administration" can be more work, less work, or about the same work as classic systems administration. That's why carefully running the numbers first should be necessary.
Oh, sure. Offshoring email is much easier than running it yourself.
The same isn't true for less standard kinds of service. The more standardized something is the easiest it is to decide what to hire, troubleshoot, and learn to configure your options. The less standardized it is, the harder all of those things become. VMs are very standard, email servers are less so, but not by a huge margin. Web accessible disk space and on-demand interpreters are completely non-standardized and a hell to do anything with.
Also, some services do need more upkeep than others. Email is one extreme that requires constant care, file storage and web servers demand much less attention.
