Yeah true while it is 70-80% on the 3E, the G2 is closer to 90-95%, so let's say at best a 25% increase, or +15mW. Say a keychain pet toy laser you buy from a vending machine is 5mW, that would be an increase equivalent to three of those. Not all that much power difference. Brightness wise, you'd be lucky to notice a 1.25x increase side by side.
Also the main reason is this... their built in lens has some silicone caked around it to help keep the lens still during normal use. Normally in the hobby we have springs to do this, but their host assemblies don't really fit well with them. The new lenses wouldn't have that, so you'd find yourself needing to adjust the focus more than you'd expect. Speaking from experience unfortunately...