How many people will there be in your party?
If its just two, then I would say no, it’s not necessary. You can easily walk up and down the aisles and find a nice spot somewhere in the middle and perhaps, near the front if that is your desired viewing area.
Many times, people get greedy and selfish and take up a lot of space… Which makes it easy to find a spot. Even on the busiest of nights, the two of us have always found a spot because of this… But more than “two” makes it a little more difficult ;^)
Now, without the package, you could be waiting for at least an hour or so because Fantasmic! is ALWAYS well attended, no matter what time of year. So if you have a large party, then I would recommend the package if you would like to avoid waiting 1-3 hours to guarantee a spot inside the stadium.