I was a little surprised to see that this is even a question. In the U.S., where freedom of religion is enshrined in our constitution, any religious celebration should not be up for debate. Those who celebrate Ramadan should feel free to do so, and it makes me sad to think that some would even think of restricting others' religious practices.
No, the celebration of Ramadan should not be discontinued. In essence it is basically like any other holiday that Christians celebrate to honor teachings passed down by Jesus. Religious followers can be either good or bad depending on who they are as a person. Taking away any religious holiday would not make Muslims or Christians behave in a better way because believing in a religion does not make you automatically good or bad. That is determined by your actions toward your fellow man.
Ramadan celebrations should not be discontinued. We are a nation with a constitution that guarantees the freedom of religion - in particular religious expression. That means one is free to express their religion whether others like it or not, so long as it does not infringe on the rights of another.
The government should not restrict any religious celebration at all. If we were to try to stop a certain faith's religious celebration, we should also consider the possibility of completely stopping Christmas celebrations as well. This is just not fair to the people of the Muslim faith, so it should not be messed with.