For business email address
Having your own self hosted paid email address guarantees you some level of security and freedom also. Plus a business having it own dedicated email servers show some level seriousness and professionalism. So if you are truly serious about your online brand and reputation then you need to make you buy a .EMAIL domain name and register your own self hosted email address.
For personal Email address
Just to show how classy you are and how much esteem you place on your name, you could easily register your private email server for a very low price using a .EMAIL domain extension.
For email ISP provider
With the restrictions being set by popular free email server providers around. Most people will prefer to opt in for another free provider with all the freedom needed. You could easily become that provider and save people from these restrictions. All you need to start with is to register a .EMAIL domain name for the website and take it from there.