Filters are one of the most important and widely-used circuits in all of radio at any frequency. Understanding how they are specified and used will make you a better electronics designer, whether you build your own or simply buy them from a vendor.
A casual observer might think that wireless systems consist primarily of filters connected by the occasional bit of circuit. Block diagrams of transceivers often include as many filters as any other function. This is true at the system level, just as it is at the circuit level — and many circuits behave in a filter-like way, whether intended to be a filter or not! That makes understanding filter basics important for wireless success.