If you can read 'em, and identify which family (of possibly many) by that name they're talking about, and when (a lot of them are rather missing minor details such as dates), then I figure they're better than nothing. Also, even if they're wrong (which, well, how will we ever know? but anyway), I think there's value in having them deciphered and charted/entered in a publicly-accessible place, so that people don't need to keep re-inventing the wheel.
But speaking of re-inventing the wheel: aren't the big nobility compilations (Nagy Iván etc.) based at least partly on these genealogies? That is, haven't these been deciphered and charted already?