Are you making assumptions about how web-savvy your customers/users are? Two examples for consideration.
We were in Europcar the other day to rent a car and a gentleman who was probably in his late 40’s was being explained the options of how to pay for road tolls. The first option mentioned was that he could simply go to the tolls website to pay. He threw his hands in the air and expressed that he knows nothing about websites. The option presented next was thankfully a lot more palatable, paying via entering credit card information over the phone.
Just over a year ago I was involved in putting a site together for a closed group of invitees and we thought it was reasonably intuitive to use. What we didn’t consider though was that some of our invitees were not used to signing up to websites and consequently they had never had to think about what their username would be or what picture they would use for an avatar (not to mention the process for how to get it onto their computer and then onto the website). For a subsequent event, we took this onboard and generated usernames and passwords up front and provided these to the attendees, and cut down the amount of information we collected, with additional information such as avatars being on a more detailed profile page. We also tested the process this time, and consequently had a lot more success.
It is very easy to make assumptions, so force yourself to step back and look at your product/service from a different perspective. Even better, test it a wide variety of people.