It's because it normally takes forever for Ash to get his sixth Pokemon. It's nice to see him getting it before the fifth badge so that he can actually train it well enough for the Isshu league. Unlike the case with Gible.(Sorry folks)
(Please don't take this the wrong way, this isn;t an attack, it's just a general statement)
Technically, normally Ash gets a team of six before the third gym. He did in Kanto, Johto, Sinnoh, and now Isshu, the only region Ash took forever to get his sixth Pokemon was in Hoenn.
On Topic: I'm excited for Meguroko, even though I originally wanted it to go to Iris.
I wonder if the other eggs will be given out too... Maybe one for James/Jessie and one for Shooti?
Then maybe James/Jessie will decide to do Gyms and be Ash's third rival...
Ignoring that last bit, I think it'd be cool if the three eggs went to TR, Ash, and Shooti, and then Ash's Meguroko/Waruvile/Waruvial and Shooti's Whatever will be rivals...