Maybe I am looking at the wrong companies, but it seems that fewer hosting companies are offering affiliate programs...most tend to offer reseller accounts instead.

Is my observation correct, and if it is, why do you think this is the case?

Because reseller accounts have more profit. Why simply get paid once when you can get paid every month?

Webhosting companies have a lot of work involved with affiliate programs. There is a lot more work, in making sure everyone gets paid for everything, everymonth. Resellers have to support their own clients, so they don't require as much attention in most scenarios. Not always true though.