Bayern was really not that dominant but there was no team ready to make use of that. Dortmund was a joke at the end of the season, it was unbelievable what they did and also didn't deserve it then.
Leipzig is consistent yes, but it's never enough for them to lead the table and stay there. They are among the top four and that has been like that for quite long I think, but they could never be a threat to Bayern Munich in the race for the Bundesliga title. For 5 years in a row they finished in the Champions League qualifiers, but every time it was quite the distance to Bayern Munich.
It's difficult when the difference is so stark in terms of mentality and strength that even when there is an opportunity, it sometimes seems to be wasted.
For example, last season where it should have been easily obtained by Dortmund because of the determination they only had to win 3 points when they were quite favoured but in the end everything returned to belong to Bayern, which is irrefutable evidence that clubs other than Bayern in the Bundesliga seem to lose hope in the title race.
Leipzig in terms of performance I would not say they are stable but they can always be in the top 4 at the end of the season.
The start of this season they did better than before but I agree with you that it won't be a reference point for the title race because in the end all they're after is probably the top 4.