We understand that many people using the web do not have e-mail accounts. You have to keep in mind that some people are using a friends computer and such things. An e-mail address is no good to them. It is important to also list your web page if you have one. A web page is on the web 24 hours a day.
People go on holidays and such things and it can take days, to weeks to hear back.
Also we will want to know this information later because people have a habit of moving. The move everything from the web page, to changing the e-mail address, to changing the street address. The best researcher indexes allow a person visiting the page to quickly determine who their closest cousins are. This is done in various ways. One way is to group the researchers by family.