"Keep your spam out of my mempool!"

Are you running a lightning node? What if a channel counterparty tries to defraud you by publishing an old channel state? In that case you need accurate fee estimation.

Your justice transaction will have to beat the dickbutts in miners' mempools. In order to beat dickbutts, your full node needs to know about dickbutts and what they're bidding. If you're ignorant of dickbutts you'll get fucked by dickbutts.