It is obvious we have a fundamental disagreement here, so I will not attempt to convince you any one way; I am merely going to tell you my philosophy.
Yes, you get matched up with the same clubs frequently. However, these clubs have different players, which can result in different tactics and different types of battles. It's like a chess match between managers; how do you try to get the upper hand over your rivals? Maybe you learn something from them the last time you've played them. Personally, I find rematches highly engaging and interesting. One way to put this is: do you think Barcelona and Real Madrid get tired of playing each other? No, they play each other because their matches make each other better, and the storylines from season to season between them are compelling.
What a level signifies to me is that it represents how often you have performed well in the League. It is a source of accomplishment to have a higher level, because it means that you've performed well for many seasons. While it doesn't change the mechanics of the game itself, it means that you're playing other managers who have also gone through the struggle of advancing to these higher levels, and so the competition keeps getting tighter as you have to beat other managers who are more and more experienced. I am a big fan of this incremental challenge, and it is pretty much the main reason why I have played this long.
I think there are some points that you make that are valid. I think Nordeus could do more to shake up the Leagues, since there are often lots of managers on one level that you never get matched with because of quality. However, I would much prefer to have the current system, where you develop relationships and rivalries with other teams as you compete with them more, as opposed to a system where you just match up against teams at random, and you never have an opportunity to really build anything meaningful with any of them.