Thanks to Maya (Invincible), I've been reading some Abraham Hicks materials. It's not that you can't say "I want", it's just how you phrase it. For example:
"I know what I don't want, what is it that I do want?"
"I'm feeling negative emotion, which means I am not in harmony with something I want. What do I want?"
"Something is important here otherwise, I would not be feeling this negative emotion. What is it I want?"
I put the above phrases in quotes because I've been taking notes as I read and those are from Abraham Hicks materials.
Another example (I'm paraphrasing here) is saying something like "I want it to rain". Don't leave the statement just hanging there, say why you want it to rain. In other words, "I want it to rain because we're having a severe drought and the plants, animals and people need some water."
So...it isn't wrong to say "I want" per se. You just have to back it up with reason why you want it.