@Iketani Iridium  
Oh yeah, I saw that commercial on TV. I kinda expected them to go and do that, since it’s Christmas and Toys R Us is obviously a toy store.

@Background Pony #7E75  
There are actually quite a few set pieces that would translate really well into lego sets. Canterlot as you mentioned, Sister’s Castle, Twilight’s Castle, Filly School, Twilight’s Library pre-explosion, etc.

@angrybrony  

As Iketani Iridium pointed out, in the fall of 2011 Hasbro launched their own line of construction toys (Kre-O) that are similar to (and compatible with) LEGO’s brand of building bricks. Prior to that I remember there were a number of fans hoping LEGO might pick up the license to do some official MLP themed sets, but that became much more unlikely with Hasbro’s competing product on the market.
 
It’s a shame though. Forget throwing money, I would have delivered bundles of cash to Hasbro’s door by forklift for some quality MLP LEGO. Canterlot Castle is just begging to be one of their higher end, extremely detailed creator sets.

@angrybrony  
Because Kre-O was Hasbro’s fake LEGO.
 
It’s RIP now, so this could happen.
 
After all, in the Toys R Us Black Firday Ad on YouTube, we saw LEGO Dimensions Batman talking to a Ponk plush.

Man, do I wish we could have Lego MLP.

My headcannon now says that Lego Ditzy/Derpy speaks only in signs like Wile E. Coyote…

how is lego my little pony not a thing?

I can’t honestly tell is this was done in CGI or Legos