It isn't. Games not involving the likes of Bayern, Dortmund and one of Leverkusen/Schalke/Hamburg/Bremen (who ever of them has 'their season') are a) totally one-sided or b) totally boring.
Simply because there's a gap between the cream and the middling teams doesn't mean the middling teams don't have quality. Look at how well German teams fare in Europe each year. The likes of Hannover, Monchengladbach, Stuttgart would clean-out West Brom, Fulham, (us) with ease.
It is a top-quality league overall. Highly fan accessible and extraordinarily well managed. As the Germans do.
The whole country is as tedious as fuck though.