One of the strong reasons may be because Vincent Company was once Pep Guardiola's assistant so Bayern Munich thought they wanted to try his coaching system and use strategies like Pep's and Pep has also said that he has the ability to lead if he is supported by great players.
Bayern Munich already has great players in it so he can use all his abilities to strengthen Bayern Munich next season. Apart from that, there is great hope that he can restore Bayern to its former glory when leading the Bundesliga without any club threatening Bayern at the top anymore.
Previously Bayern Munich had been coached by Guardiola so I think the reasons you say don't make sense to me, apart from that so far Kompany has only been a player under Guardiola coaching and not as an assistant like what happened with Arteta, I don't see the style the game owned and implemented by Kompany so far is similar to the game used by Guardiola in the manchester city, so there is indeed a significant difference in terms of the two of them coaching so far, Bayern Munich recruited Kompany after they couldn't find another coach who really wanted to train Bayern Munich, apart from that style The game implemented by Kompany at Burnley is considered to be suitable for Bayern Munich playing style so far.
The club that can still be a serious threat to Bayern Munich is Bayer Leverkusen because the club will still be coached by the same coach so the strategy will probably not be much different from last season, although some may be changed to make it less easy for all opponents to read. I also think that Vincent Company has the ability to train Bayern Munich's players next season, but this will also be quite difficult for Vincent Company because considering that Bayer Leverkusen can still be better than last season in the Bundesliga next season.
What you say is true at the moment if we look at what Leverkusen is doing this season, but I think Dortmund, Leipzig and several other teams will also be quite strong opponents for Munich next season, we all hope Leverkusen will still be able to defend their performance next season and will make that the Bundesliga will continue to be competitive and no longer controlled by one team as previously.