I understand why many people don't accept that a consecrated host is sacred. If you're not a Catholic, you may well feel that "It's just a cracker".
Having said that, common decency requires that you not stomp on other people's religious symbols. You don't handle a Koran carelessly, you don't litter on the Native American's sacred sites, you don't deface a Japanese ancestor's grave.
I'm also completely flummoxed by the people saying a consecrated host is JUST A CRACKER, so why is everyone getting all upset?
Would it be okay if I spraypainted obscenities on your mother's grave because it's just a piece of highly compressed igneous rock with some lines chiseled into it? How about if I photoshop your a photo of your now-grown child onto a piece of child porn, because after all, no one's actually hurt by this--it's just a piece of paper.
If you reduce symbols to their base physical constituents, then of course it sounds silly to get all excited about them. Nonetheless, you'd probably be pretty damn upset if someone dug up a relative's grave and desecrated the corpse on the grounds that it's just some rotting meat.