Read several things in here:
1. Bayern buys the biggest talent from their national rivals
Let's get this straight. Who have been rivals during the last 5 years? I'll rate everyone within 10 points rage at the final table.
Season 08/09:
1. Wolfsburg (69), 2. Bayern (67), 3. Stuttgart (64), 4. Hertha (63), 5. Hamburg (61), 6. Dortmund (59)
From these teams Bayern bought Gomez (Stuttgart) and Olic (Hamburg). They also sold Hummels to Dortmund after that season (he was on loan during the season at Dortmund).
Hottest transfer in that season were Marin (to Bremen) and Gomez (Bayern).
Also Bayern integrated Badstuber and Müller to the team.
Season 09/10:
1. Bayern (70), 2. Schalke (65), 3. Bremen (61)
From these teams Bayern bought none. However they bought Gustavo from Hoffenheim, as they lost van Bommel.
Hottest transfer targets in that season were Khedira (Real), Dzeko (City), Özil (Real) , Boateng (City).
Also Bayern integrated Alaba to the team.
Season 10/11:
1. Dortmund (75), Leverkusen (68), Bayern (65), Hannover (60), Mainz (58)
From these teams Bayern bought none. However they bought Neuer from Schalke, as they needed to adress their keeper problem.
Hottest transfer targets in that season were Sahin (Real), Vidal (Turin), Cisse (Newcastle), Schürrle (Leverkusen).
Season 10/11:
1. Dortmund (81), 2, Bayern (73), 3. Schalke (64)
From these teams Bayern bought none. However they bought Mandzukic from Wolfsburg which was rather surprising.
Hottest transfer targets in that season were Kagawa (Utd), Reus (Dortmund), Marin (Chelsea)
Season 11/12:
Well not much sense as none was in the defined 10 point range, but let's say it'll be Dortmund; then we have the Goetze transfer who probably would have been the hottest transfer-target .
--> That written I suggest that Real Madrid is buying all the talent from Bundesliga (Özil, Khedira, Sahin) vs. Bayern (Gomez, Neuer).
If I missed a transfer, I am sorry. I just verified for transfers to Bayern, rest is from my mind.
2. Bayern is just doing it for weakening opposition
All past transfers have raised the quality strongly or was needed. To be fair you can argue that this is not the case for Goetze (nor Lewandowski, but I refuse to believe he'll join us this summer).
On the other hand you need to realise that in Germany you need to have at least 12 german players in the team and at least 8 players who have been developed in Germany. Fulfilling this quota with players who really can have an impact to the team requires transfers.
For all top-transfers made by Bayern during this time, I fully guarantee to you that they would have been transferred anyway. Gomez, Neuer, Goetze would have easily gotten contracts at all top sides in Europe.
3. Bayern is weakening opposition with their transfers
The money they have been paying for their transfers has been enormous. Let's take Dortmund with the Neuer deal as an example. Schalkes biggest problem at that time has been the lack of depth in their team and their ability to replace people. 35 Mio. EUR could have helped a lot. Also in my impression Bayern has never screwed someone at transfer negotiations but has always paid considerably fair prices. No keeper has ever had a higher price tag than Neuer, Gomez had the record fee at that time, 15 million for Gustavo have been huge, ...
4. Bayern is disgusting
If they are, so is everyone else in a free market. Who is not trying to get the best possible for fair prices?
Please show me one top team (incl. Dortmund) not buying from other (less successful) teams.
Dortmund has developed Goetze, Schmelzer, Sahin, Reus (regular starters).
Bayern has developed Badstuber, Müller, Lahm, Schweinsteiger, Alaba, Kroos (regular starters).
Not much difference, eh? Where do you think the other Dortmund players come from?
Other countries? So do Bayern players (Ribery, Robben, Boateng, ...)
Other clubs, not directly competing? So do Bayern players (Dante, Gustavo, ...)
This is just pure dislike driven hypocrisy. If you want to strengthen the league you need to strengthen the teams by higher revenues, not by weakening Bayern. This might happen due to new deals for TV revenues, better balance between clubs with champions league income and professional management.
Wolfsburg is cofinanced by Volkswagen, which is the same like a sugar daddy. Dortmund has everything necessary to grow as a club, so do Berlin, Hamburg, Stuttgart, Schalke. The mismanagement is not the fault of Bayern. The clubs have every chance to become constant contenders.
By the way; Bayern buying players is also just a temporary problem; having the squad they have at the moment it will become more difficult to strengthen is with international mediocre transfers like Gustavo, Dante, Mandzukic. Bayern will in future raise investments into one single player and reduce the amount of players needed.