We are only offering 6000 BRO per btc for a 48 hour period to give others a sufficient chance to buy-in at the bonus level. After that period, we will be offering 3000 BRO per btc until the "coins sale" closes or we reach a sufficient number of btc needed to complete the project. We will close the sale early once if we reach that number early, we do not want to accept any more btc than necessary to finish and showcase the products.
Do you suggest a longer period than 48 hours?
think the reason is to give a bonus to those who invested already...
The plan doesn't actually do that. They should have added a small bonus for people who have already invested, like 5% or 10% (6600 or 6300 PRO/BTC).
Also, having some coins left over for "Remaining coins will be sold at the public release of beta software", is going to encourage a wait and see investment strategy after the first round of speculators jump on the 100% bonus.