I could see that future resale would be affected by having your info engraved on the lower. You might even be better off selling the components and destroying the lower or reverting it to a Title 1 gun.
I know that Daniel Defense has done runs of Form 3/4 registered SBR lowers. Those would obviously be preferrable for resale value as nothing but the Daniel Defense info would be on the receiver. I may go that route when I get around to doing an SBR lower. I want one in case I ever decide to sell my RR M16, but want to keep the short upper.
Yes, I can see future resale value as a reason you would not want to engrave.