During the 17th century the zischägge/hungarian pot seemed to gain greater popularity over the burgonet especially among the cavalry.

Was it just a fashion thing or are there any other more practical reasons for this developement?

Strongly suspect that it was for both reasons of economy and expediency. They could be turned out in pieces and quickly assembled by people with little skill. Large numbers of men could be so equipped with at least the minimum protection. Of course with the coming of standing armies, equipping large bodies of men quickly became a necessity.

Both quality and style varied greatly. Some were very beautiful (for those with deep pockets) and others were strictly a utility piece and were just plain homely. Over the years, I have heard these helmets referred to as, lobster tail pots, pots, zischagges, lobster tail burgonets, harquibusier pot, you name it.

Incidentally, the first modern standing army was that of the Ottoman Empire during the 14th century while jolly old England had to wait until the mid 1680s.

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Regards,
Dan