Re: your funeral ............
well, in my opinion, i think a tombstone is beneficial for family. when they come to your grave, they have something there. and when they're kids come, and their kids...so from generation to generation. usually graves get eventually wiped out, but there's some sort of memory still there.
like with my grandmother, i know where her grave is. but will my children..? will my children's children. so coming from that point of view, i think it's a good idea.
but yes, i agree with you that you can use the money elsewhere...i rather my kids remember where i was buried so they can come with their children...