So you're basically upset because the developers are releasing content that isn't even relevant at endgame a mere week later than the content that is actually relevant at endgame.

The devs aren't staggering BLU because of some ulterior financial motive. They're saving you from yourself.

(But really, the real reason is probably related to BLU having a much higher chance of having something so bugged out the arse that they'd rather do emergency patches for BLU week 2 instead of ticking off everyone who doesn't care about BLU at all and trying to do other content during week 1. And let's be real, everyone expected BLU to be released towards March/April, not a week after patch.)