I don't think we really need 64bit but, on the other hand, maybe one day some LE or addon code may conditionally want to use 64bit if available and perhaps result in better performance for some task that can effectively use 64bit. if nobody makes sure 64bit continues to build, that would be a pity. Also, the high end TV boxes have enough resources to run 64bit. And, somehow, one may believe 64bit software on 64bit hardware is cool :-). Myself I have built (and run) 64bit upto 7.0.3.12g (skipped h) and I would like to be able to continue to do so.
Don't worry, I make sure that aarch64 is buildable. I will also add the mem leak fix to my 7.0 branch.