In a way Johto's level curve says something deep about life which may hit too close to home to be appreciated.
I don't necessarily agree that this is a good thing, but I do agree that Johto's level curve is at least somewhat intentional in its design. When factoring in the clock and the day/night system, the way I see Johto is that it's encouraging to play the game slowly, taking it one day at a time. In a sense, it's kinda similar to how modern mobile games handle daily events - play a little bit each day, check for any new events like trainer rematches or swarms, and either progress more through the game or set it down for the next day. You're not meant to play it in large sittings, but take it one step at a time, training and catching over a long stretch of time.
I don't think it works well in practice, granted - I think it's too slow and your options too limited - but I think any discussion of Johto's level curve needs to take the ethos of it into account. I'm not saying you should check all your opinions at the door, just that it's not meant to be played in the same way as the games that came after it. HGSS preserved these elements, and arguably enhanced them by virtue of the Pokewalker, which gave you another means of connecting with the game on a daily basis and weaving it into your daily life. There's also a few more mechanics like the Safari Zone, but the Pokewalker mostly stands out to me in this way. It's a bit tangential to the level curve itself, of course, but I think the same broad idea applies - you're not meant to go through the game with a rigid team of 6, marching towards your goal of beating the Champion, but slowly building up strength one day at a time. There's merit to that, even if I find the execution shaky.