Conflict between Brahmajala Sutta and current Buddhist practices I'm very confused about this sutta ( http://suttacentral.net/en/dn1) specially in the part "Mahāsīla"

Many of what the Buddha stated as wrong livelihood is very common in some Buddhist centres these days, things like: Astrology, selling lucky gems, offerings to deities etc... if you read the list in the sutta you will see it.

Is this sutta not part of some Buddhist cultures? Am I interpreting it in the wrong way? Or is it simply being ignored??
You are correct. The Buddha spoke out against such things because it corrupts the right livelihood of Monks because people will support Monks to get them to preform fortune telling for them or other such things instead of supporting Monks for their virtue and practice.

Most laypeople in Theravada countries don't engage in study of the canonical texts to any significant degree and they simply don't know better, and perhaps the Monks involved don't know it either. If they do and continue to do such things, I think it is very unfortunate.