I also think you're overreacting.
And I have to ask you:
that way nobody is disappointed when they don't get a basket from their favorite aunt and uncle.
Are your kids really disappointed? And, who is mentioning these gift baskets? You? Them?
I think when our kids have relatives who are disappointing (whether it's a big a deal as grandma favors the other cousins; or if it's that wonderful aunt & uncle keep forgetting the Easter baskets), it's our role as parents to help our children live with that disappointment.
That means not ever mentioning, ourselves, that A&U haven't delivered the baskets.
(And not rubbing our kids' noses in the fact that Grandma doesn't love them best--no complaining in their presence, etc.)
And it also means modeling the proper response when someone is disappointing
("Well, unfortunately, we're not going to be able to change Grandma, so let's turn our love and attention to someone else, instead of always trying to get her to love us more. Because that hurts, so let's not keep doing it. Let's adjust our expectations to match reality; that will actually hurt less.")
("yes, it's disappointing not to get the Easter basket, but remember that it's not very attractive to be complaining about not receiving a gift. And we've actually gotten to see them in person, which is so much better, so you're coming across as though only the gift matters to you--that makes you look greedy. And as far as the stuff goes--you have all the chocolate and cheap toys any one kid needs. In fact, if I hear you complain about it again, I'm going to make you go in your room and -pick up- all those cheap toys you have.") EDITED TO ADD: I realize this is a little stern; of course I'd use something more sympathetic depending on the kid.