The higher data rates are hoped to at least partially compensate for the higher power. You burst data at high power, but for less time. Also, there are retransmits that occur now, if a packet is corrupted. Higher power should result in fewer retransmits, which will help with battery drain. Battery life is hoped to be better, even with the higher power.
There are regulatory limits on how much RF a device can send into the body. These are called SAR limits [1] and they are not changing. I was joking about the body effects. The legal limit is not changing. But devices that used to be further below the limit, will now be closer to it.