Nobody WANTS to wait, but it is a fundamental necessary evil of the convention. How much of your time did you spend in line at Anime Expo? I heard it was a 1 hour wait for registration, a 2 hour wait to enter the exhibit hall per day, a 20 minute bag check line every time you wanted to re-enter the building, and a 20 minute line for food.
The lines for Pre-Reg and At-Con-Reg were homogenized this year making it seem much longer of a wait. Chances are that they found the ratio of the two types to be too small for the dedicated human resources. Instead of getting 5 people to handle exclusively At-Con's very quickly, they chose to have only one person sort the people and spend more time at just one person to register them.
How much time did you spend walking in traffic? Assuming that you are human, you walk at about 3 miles per hour or about 4.5 feet per second. Nobody walked that fast, more like 1.5 feet per sec. So some simple number-crunching means that you wasted 33% of your time, compared to walking normally, for every time you were walking in traffic. How long did you wait for friends to meet up in the convention center? Well, they still had to travel in traffic too, so that's another 33% more of your time.
So on a regular con day (9 AM to 9 PM), you lose the opportunity to do something awesome for about 5 hours worth of your time. That’s 40% of your time at the con.