Do you ever change the fluid in between brake jobs? This crispness to the braking may be because of the new fluid. The old fluid may have had air in the lines. Some caliper designs sometimes allow a little air to get "slurped" past the seals during brake release. I'm not sure if that includes Mercedes brakes.
New pads and rotors should actually have the opposite effect of what you experience, unless the old parts developed a glaze. The system should be somewhat soft until the new parts are seated.
95 E320 Cabriolet, 131K