Many reasons some I can think of is if that person is say a musician or artist and wants to setup there online persona. Then they will want to have there own dedicated site named as they wish with email addresses that support it.
If someone developes webpages for a hobby or wishes to break into that field then they may well setup there own dedicated site to show off there talents.
Maybe even as simple as just to get an email address with [email protected] or the like
Like beynac, I'm always testing my latest pet project on my webspace.
To answer question, realist - it depends what you want to go for. My ISP incuded a free domain name and fully-featured webspace for no extra cost. I have some other sites hosted with other providers, which are competitively priced. One is £19 ex vat per year and is well featured, but with a few email features missing (such as forwarding) and the other two are about £50 per year.
for an individual to want his or her own domain name. There's certainly no other reason, unless he/she plans to publish a web site. It's become very much the thing for many people to have their own personal web site, but in truth the large majority are of interest only to the publisher and his/her friends and family.
It's not difficult to obtain a domain name - there are any number of companies who will register one for you for a few pounds, and for a few pounds more each year they'll probably give you a mailbox on the parked name, so you can use a personal email address.
If you want to publish a web site on your name you'll need to have it properly hosted, and that will incur an annual fee - again not a large amount.
Another reason for me and my buddies anyway is for a clan site the use being we can publish battle times and dates and e-mail other clans for competitions.
for online gaming its a very usefull tool as we (our clan) can invite other clans or groups to battles/challenges and post up the time and date and with the e-mail using the same adress as the site we can e-mail clans with times and dates and they know who is challenging them.