This controversy is fascinating because it is almost entirely about symbolism, not anything concrete.
The purpose of a minaret is to have an elevated platform from which a muezzin makes a public call to prayer. Over the centuries they have become as distinctive a part of mosques as bell towers are for churches, but as with bell towers they are not necessary from a religious perspective.
There is a secondary purpose for a minaret, which not too many are mentioning: to ensure that the mosque is the tallest structure, and certainly the tallest religious structure, in the immediate area. Muslim countries often enforce laws that make it illegal for synagogues or churches to be built taller than mosques. Christian countries have historically enforced similar laws making it illegal for other religious structures to be taller than churches.
The third purpose for a minaret is simply because it is an architectural feature that has been associated with mosques in many strains of Islam for centuries, similar to domes. It is traditional, even if the call to prayer is not done in all cases.
In Switzerland, there are already laws to severely limit the Muslim adhan, the public call to prayer. The four existing minarets in Switzerland are not used for that purpose, from what I can tell. Therefore, in Switzerland, the minaret is a purely symbolic structure - and it is this symbolism that is causing the entire controversy.
Muslims will argue as to the symbolic value of minarets in the Western press, downplaying the secondary purpose and playing up the tertiary. Mosques can be built without minarets and this ban in no way limits their freedom of worship; on the surface, this Swiss ban is not about freedom of religion.
However, the opponents of the minarets are being equally deceptive in hiding their motivation. They pretend that the ban is to preserve the skylines of their towns, but in reality the movement to ban minarets is completely about the fear of Islam and Muslims. The initiative came from right-wing and ultra-conservative parties that are often associated with xenophobia. Their most famous poster against the minarets doesn't even try to hide their real anti-Muslim agenda, as the minarets are consciously drawn to evoke missiles and the woman wearing the abaya plays on fears of Muslims.To them, the minaret is a sign of growing Islamic encroachment on their land, and Muslims are regarded as undesirable outsiders. The minaret is no less a symbol to them than it is to Muslims.
Without symbolism, the existence of minarets is no more offensive than their ban. In this case, each side's symbolism is the same: minarets partially represent Islamic dominance and the opponents fear that dominance.
Symbols are inherently irrational, but their power is undeniable. The media, trying hard to be rational, downplays the symbolism of both sides, and therefore the passion that this issue evokes is lost.
In the case of Switzerland, the ban clearly is discriminatory against a single religion. Unless the ban is extended to include church steeples or other largely symbolic tall structures it should be rescinded. On the other hand, individual mosques being built in Switzerland must go through the same zoning rules as other buildings, which take into account esthetics and local sensibilities, and which would make the construction of new minarets relatively rare anyway. By raising this local issue to a broad-brush national ban, Switzerland is showing that it is not immune to bigotry and that the famed Swiss neutrality is a myth.