Weird Al predicted all this woke bullshit back in 1999 with The Saga Begins.
You thought it was just a funny parody of an awful movie? He knew baristas with purple hair were going to cancel white people.
do you see, this junkard slave
isn't even old enough to shave,
but he can use the force, they say
ahhh do you see him, hitting on the queen,
though, he's just nine, and, she's fourteen,
yea he's probably gonna marry her, sooomedaaayyyy~
The chemistry for Anakin and Padme's eventual romance was well and truly fucked up before the bad writing and directing (they're both talented actors that had a bad situation, that's my hot take) in Episode 2 happened.
too many yes men from the studio forcing every little thing lucas thought up into reality. there should have been somebody to balk the first time he said "what about a child queen dynastic political intrigue plot in our pg space action movie series marketed for kids"
Lucas and Spielburg once had a documented conversation before Raiders of the Lost Ark was made where they argued back and forth whether Marion should have been younger. 
Aging up Anakin to 13 or 14 would have improved the movie immensely, like there's no reason for him to be that young in the story. But that's just scratching the surface of the bad choices made in that movie.
I think Lucas wanted to sell toys and memorabilia to a crowd that was Jake Lloyd's age. And that was that. 
That was probably the justification but it's an incredibly silly one, kids don't care if the main character is the same age as them. Luke Skywalker was 20-something and plenty of 9 year-old boys were able to identify with him. And as long you put lots of cool spaceships and droids and shit then kids will buy the toys lol.
I typically identified more with the cool robots than Spike/Daniel in the Transformers cartoon, that's for sure.
Though I wouldn't have said no to those awesome exosuits featured in the 80s movie.