No offense but in my opinion, this is wishful thinking. IMO you dislike the clubs you call plastic and want them to be responsible. I mean, even if they were and you just removed them from the league, it would take clubs like Frankfurt, Schalke or Hamburg at least 5-10 years of better management than they had in the past two decades to get on the level of even Dortmund. And chances are that Bayern still grows faster in the same time window, widening the gap further. This is a natural monopoly - the longer it goes on, the more the financial prowess between the top club and the rest will grow. Bayern have already won 9 out of 10 and it is not going to become better but worse, it is the nature of the system. You might as well declare that Bayern has won Bundesliga at this point and move on. Even if they lose a title once in a while, they will bounce back harder than ever. And such a league will generally grow slower than a league with an actual title race.
The last three season Bayern finished on 78, 82 and 78 points. Those are achievable numbers for Dortmund and there were plenty of things they could have done better to reach that, e.g. sacking Favre, who is not a title winning coach, earlier, not signing Meunier to replace Hakimi, not spending €50m on Schulz and Brandt the year before, and not spending €20m on Wolf and Balerdi the year before that. Now of course it's not realistic to expect that Dortmund don't make mistakes, but add another one or two Dortmund sized clubs in the mix, or even just don't have Leipzig snap up Nagelsmann and it might not have been 9 titles in a row for Bayern.
The current situation developed over 2-3 decades, it's not realistic to expect a short term fix, or really for any club to catch up to Bayern if they keep doing good work. That's life. But having more clubs the size of Dortmund would be a considerable improvement.
Regarding "plastic" clubs being responsible for keeping the sleeping giants from consistently making top 4: Dortmund proved that we're no match for a club of that magnitude once it gets its act together.The times we made top 4, we were there because we used our money wiser than the rest. Also, those clubs weren't kept out by us, they sometimes didn't even make the EL and many of them were even relegated recently. They're terribly managed clubs and they have been since decades - this is the very thing that allowed Bayern to gain so much ground in the first place.
Dortmund just won the lottery several times over with Klopp: in terms of coaching, in terms of development and in terms of PR. That was a proper miracle that other clubs can't expect to replicate. Plus there was no Leipzig blocking their way. It's an entirely different situation now. Bayern, Dortmund and Leipzig have a subscription on top four spots, then you have Leverkusen and Wolfsburg, who can just maintain high wage bills regardless of their actual success on the pitch..
You have three to four teams fighting for that fourth CL spot, which is so essential for financial growth and two of them can just maintain huge (relative to their two competitors) wage bills or in Wolfsburg's case just spend completely anticyclically.
Gladbach make top four and can only loan two flops from other clubs, meanwhile Wolfsburg finish 7th and just buy Baku and Lacroix.
You talk about spending money more wisely when the latest wage numbers are Leverkusen €140m, Wolfsburg €124, Gladbach €104m, Frankfurt €84. And on transfers? €26m on Schick, €32m on Demirbay, € 17m on Palacios, €18m on Paulino, €12m on Weiser, €24m on Alario, €17m on Retsos, €21m on Dragovic. I don't think I have to talk about Wolfsburg either.
Meanwhile Gladbach - in their entire history - have bought two players for over €15m. Frankfurt have two signings over €10m. I get that you want to make this all about Schalke and Hamburg, but they got what was coming to them and no one is shedding a tear for them. The problem is that other big clubs can't take their place, because there are these buffer clubs, who significantly outspend them for no good reason.