Nope.
Several approaches do not even include marker beacons (vor, ILS/loc/DME, RNAV) and increasingly it seems more marker beacons are being taken out of service. So, obviously you wouldn't need a MKR bcn to fly those approaches.
The gns430w can be used as an acceptable means of DME, therefore you can use DME to identify several fixes in IFR flight and (i think) including the MKR fix (if you needed) or a lot of times a radial can identify the MKR fix.
Axing the marker beacon locator and antenna, opens you up to a few more audio panel options (par100ex, gma 240)