Of course people are still grumpy that the "this game is simpler" games are, in fact, simpler, why am I at all surprised
Anyway, a side note about the trainers in the showcase - they're probably set lower level than in the real game specifically for the showcase or as part of a demo version. They started her off with a specifically set party of all five Kanto starters - Gen 1, 3, and this one - at Lv. 5, and an obscenely high Lv. 15 Onyx. They probably had a game plan as to what they wanted to show, and set the levels accordingly. I'm not saying I'd be surprised if they're lower here, but Cale in the original trailer was at a similar level to his role in past games, just with one Pokemon instead of four.
It's still a little early to think they're going to reduce levels and party counts - could happen, wouldn't be super thrilled with that myself, but it's not time to worry yet.
And honestly, that wouldn't be a game-breaker for me. There are plenty of ways to make it more difficult for yourself if that's what you're looking for. Pay with a full team of species that need stones to evolve and are cute, and don't evolve them - hell, I literally might make my team for the whole game Clefairy, Vulpix, Eevee, Jigglypuff, etc. now that I think about it.
Wait - if I could get an Alolan and a normal Vulpix and throw in a Pikachu too... lit