"But Jake, Pokemon is a game intended for kids! If Game Freak and Nintendo add a rival who doesn't exemplify being nice and a potential romance interest, it won't appeal to kids and their parents won't buy the game!"
If you're worried about a no-nonsense rival being the thing that sets parents off in a series that has angered people for far worse (not that we think PETA's anti-Pokemon stance makes any sense though), then you're in need of some help. There has to be a Pokemon who can teach you to use your noodle.
One of the things that led to my disillusionment with the Pokemon franchise was it rapidly trying to become more politically correct and playing it safe when it came to the rival characters. In Blue and Silver, or the rivals in generations one and two, you had an arrogant smartass and a cold loner respectively; the former bragged to you about being one step ahead, while the latter was constantly in a moral battle as he tried to figure out if true power really was all that mattered in this world.
The rivals then served as foils to you, but the majority of our rivals since - aside from Cheren, who was awesome - have either been useless or gag characters that aren't meant to be taken seriously. Remember Tierno, the Majin Buu-looking dancing oaf from X and Y who asked to call you 'J-Miester' immediately after meeting you? This was our rival?
What happened to the days where our rival gave us actual motivation to beat them? What about when our rival had some sort of character arc? Instead, we've gotten such memorable opponents like ditzy blondes, a dance-loving idiot who looks like he ate the rest of his competition, and a weird-looking girl with no goals or aspirations.
Generation 7 had a chance to break new ground with Hau... but he didn't take his battles seriously and was always happy. Again, this was our rival? How was it possible in a game that felt so jarringly realistic and emotional at times we winded up with a rival who has no character?
But hey, at least he was better than Tierno!