There most definitely is systems engineering.

A-lot of people in the Agile community don't understand engineering. Real systems engineering is pretty Agile: prototypes, design validation, a thorough testing strategy. Iteration where possible. But real systems engineering is not reckless and ad-hoc.

That said, people often practice systems engineering badly: they try to fully design something up front, and do not spend enough time on prototypes, and they don't take advantage of the value of iteration.