Lists help for people like my DS who has ASD. Unexpected gifts really ramp up his anxiety if they aren't exactly what he wants because he finds it hard to mask his true emotions and he can't handle the demands of having to act grateful if he isn't.
This year, 2 people who normally send money actually gave him gifts. Uh-oh unexpected gifts!!! Luckily one of them was a lego set he really wanted and I hadn't been able to get (he had initially asked for different lego and I'd bought it well in advance, so couldn't return it). The other person got him some books on a subject which he is also very into.
Unfortunately the person who got him the books kind of expected him to drop everything and start reading the books. This is a 9 year old surrounded by toys, so I had to gently point out the books wouldn't come into their own until after the toys were put away and it was nearing bedtime, as he reads in bed. But they didn't get it and kept on "Don't you like reading? I thought you liked [subject]?" Etc. He got quite stressed out and I had to take him off for a snack to calm him down.
Neither of the presents he was ungrateful for, but the expectation of undying gratitude for things he didnt ask for was stressful for him to say the least. Everything that he asked for and got was met with excitement and enthusiasm - even the clothes - because he'd asked for them!
I bought myself a gift from my sister this year and she paid me back. It was something I really wanted. She wrapped it for me to open on the day, lol! And my DM frequently goes off list but to her credit usually gets it right. She knows I'm quirky so buys me random shit that makes me laugh. DParents still get the big things I ask for if they can.
If you can go off list and get it right you're onto a winner. You really have to know someone to be able to pull it off though. In your case, OP, if you want gratitude then stick to the list. With youngsters it's about getting them the things they can't afford for themselves that they really want. They are developing adult tastes but don't yet have the bank balances to afford this stuff for themselves. It's more thoughtful to buy then these things that they want than it is to keep treating them like a young child who can't think for themselves.
I had 2 old aunties - one who'd press a £10 note in my hand and say "Have a good night down at the SU Bar, dearie!" with a twinkle in her eye and the other one who gave me a pound "to treat [myself] to a 99" when they cost £1.20 - I didn't love them any differently and was grateful they both wanted to treat me, but the former certainly had her finger more on the pulse (the other did not have dementia before anyone says anything, she just always treated us as young kids because she didn't know us well)! Be the former, OP!