in my 2007 es350 I have not noticed the amount of illumination ever being a problem. but i have less than perfect vision anyway and wear 1.0 corrective lenses, but use my brights when I can since I drive faster than most.
MY PROBLEM IS THE QUALITY of the lamps! Ours will just go out while driving, one or the other or even both, then we have to click them off and back on to get them on again, and they may or may not stay on. we have even been pulled over for it. I just clicked em off and on before the officer got to the car and asked him which one was off, and he said they were both fine....ooops!
I have a 2000 GMC yukon with 190,000mi and have never had this much trouble with it. the headlights on the es350 are just one of many little multi-THOUSAND dollar $$$ issues.