All things being equal, there are really no drawbacks for a high power Class D amp, other than maybe paying for something you may not need. But all things are never equal and one of those is Class D is horrible sounding if not done right (Levinson No. 53?).
An analogy to amplifier power would be: is a 2400 watt wall outlet (standard 20-amp circuit at 120 volts) too much power for a 7-watt LED desk lamp? Of course not. The power is consumed by the light bulb and all you pay for is the power consumed, not what is available. The outlet does not "produce" 2400 watts and the lamp only takes in 7 of those watts -- it has it there at the ready should it be needed. Just like the power reserves of an amplifier.