One reason you might negotiate directly is if you have a loyalty membership / status with the hotel chain — you probably don't want to book through a discount O

One reason you might negotiate directly is if you have a loyalty membership / status with the hotel chain — you probably don't want to book through a discount OTA (because, depending on chain, you may miss out on the benefits of your status), but you can absolutely negotiate the price by emailing the hotel directly, and keep your perks.