Good for you for questioning it. You are the go-to person for the family and everyone depends on you. Part of you probably enjoys this, but part of you is wondering if this is the tradition you want to continue to the next generation.
I think it's a good opportunity to talk to him about how you just swung into action but you think it's not a good lesson for the future. Let him know he's in 7th grade and able to handle more responsibility so that he can ultimately go forth from your home into independent adulthood. The next purchase or shopping trip will be something you do together. Understand that he will roll his eyes and look for an escape route from this discussion.
Then make a priority list of the skills you want him to develop, and put them in the order that is the most sensible. For starters, does he write thank you notes for gifts he receives? Does he know the key elements of a heartfelt thank you? Does he know how to deal with a gift he's not thrilled with? In our house, thank you notes started with me writing what my son said about or did with the gift, progressed to him dictating the note, and on to him writing it. By 4th grade, he could not play with the item or spend the money until the note was written, and if he still refused, I told him he had to write a letter to the giver saying why he was sending the gift back. Of course, he didn't want to lose the gift, and since he was writing a letter one way or the other, he chose the thank you note.
My neighbor has 3 kids and she has worked so hard with them on manners, eye contact, and social skills with adults. They are really far ahead of many other kids with their ability to show respect and interest. Maybe that's something you want to work on if he's not already proficient.
You say that you do all the holiday stuff - is that the shopping, or does it extend to the cooking and the decorating? The shopping may well be done for now, but for the other stuff, there's no reason your son can start to learn to do some of these tasks (perhaps with his father) - getting out the casseroles and decor, putting things away, hauling tables and chairs out of the basement, etc. What about the gift wrapping and the tags? My son and my step kids were filling out the gift tags for their gifts to others (even if I did the shopping), helping with the wrapping (handing me tape, putting on the bows, checking things off the list, etc.) and doing many other tasks standing next to me. When they got sick of it, I said, "Well, how do you think I feel? If you want to cancel the holidays, let me know."
What about household chores? "Many hands make light work." Think of the things he expects of you (and while you're at it, look at the things your husband expects as well as the things your husband does on his own). Choose 1 thing that you want to teach him and have him take on for himself. For us, the first task my son took on was his laundry.
Don't overwhelm your son - but do pick something associated with the holidays (1 prep, 1 clean-up afterwards), and then a task for the coming 3 months. When that's done and second nature, add another one. And of course praise praise praise him, and increase his privileges.
Otherwise, yes, you're creating the next generation of unappreciative family members. Honestly, you want him going off to college fully functional! Kids with no skills about organizing, cleaning up, and doing things for others make terrible roommates and dorm mates. They don't adjust well because they expect everyone to do everything, from setting up their rooms to getting laundry done to talking to their professors about deadlines! It's our job to make them self-sufficient!
But for now, expediency was the way to go!