Satoshi wants victory... or going down in a blaze of glory. That is simple. Ash doesn't want to face an easy trainer to win the League. He wants their best. He wants the ultimate opponent to earn that League championship.
Ash being disappoint could lead to false readings or foreshadowing given what Ash will later find out about Alain's connections to Team Flare. If I had to guess as to why Ash is such a good sport in the Kalos League, it's because they don't want to indicate that Ash is secretly jealous of Alain or is going to use the discovery of Alain's Team Flare connection as a means to disqualify Alain from the championship.
In fact, part of Alain's surprise with Ash is how he easily he got over his losses and just wants another battle with Alain in the future, possibly in another League and with a new team. Keep in mind, Alain's mentality prior to the Team Flare climax was to get stronger and never lose. Defeat was not an option. So for Alain to see Ash shrug off the defeat (as well as the fact that it was kinda Alain's fault that Ash was captured, tortured and nearly turned into a slave for Lysandre), it made him realize he could not defeat Ash. Maybe have victories over him, but Ash still keeps on going like Rocky Balboa.
After Ash defeated Sawyer, the Kalos League becomes a character study of Alain with Ash as the foil (and in my opinion, his better). This is why Ash doesn't get as much as focus in regards to his response to losing the Kalos League. It's from Alain's perspective. A perspective that is a running theme of XY: How do people perceive Ash Ketchum as?
And more importantly, after you win the League, now what?
What do you do when you after you win the League? And what does it mean to actually win the League after all that hype? It's the elephant in the room question. I wouldn't be surprised if the reason they made Alain the victor is because Alain offers better insights to this whole hype League victory than Ash could. Because we know what Ash would do after winning the Kalos League: Go to the next region and become a master there. He simply will not retire anytime soon.
Maybe that's why Alola League is so low key. Perhaps they realized that hyping these massive Leagues (which are used to justify Gym Battles) has made the events more important than they really are. And maybe, to prove their point of how silly it is to focus on the League, they'll make Ash Ketchum the champion victor.