1. That is never true since the anime's debut. Takeshi Shudo, aka the original head writer for Pokémon, specifically made the Team Rocket trio as something for adults to enjoy while they watch the show with their kids. It's why many fans consider them the best part of the show and why they tend veer into more adult camp and humor (like crossdressing and various references to other, older anime). Even ignoring that, Pokémon XY is certainly more action-oriented than previous Pokémon shows (with the climax being not the League but the conflict against the villainous team), and it was the first series in a long time to acknowledge death and not in a manner where the dead can come back to life (Espurr episode). As I've said before, it was outright stated by Yajima that the kiss couldn't be shown due to censors (thanks to the cultural value of the sacred first kiss in Japan) but everyone pretty much confirmed that Serena did kiss Ash when her feet lift upwards.
2. What do you expect Ash to do? Outright say to Serena that he loves her before she leaves? Do note that Serena never outright said she loves Ash to Ash. But everyone knows what she meant. And thus, fans easily figure that Ash loves her back when his eyes twinkle after the kiss. Visuals says it all.
I mean, in The Legend of Zelda: Skyward Sword, everyone knows that Link and Zelda are romantically in love with each other. But they themselves never outright confirm it. Link doesn't talk and thus we can infer based on his very expressive face. Meanwhile, Zelda alludes to a romantic confession but often in the words "care" and "together", never "love". But we know they are in love and that at the end of the game, Link decides to remain with Zelda on the surface with nothing more than a lovely smile and the fact their Loftwings fly into the sky together. All without a hint of a kiss or a love confession.
It might also help that their music theme together is labeled "Romance"...