It's surprising how much difference there can be in perceived brightness with LED flashers, like the ones used for bicycles. I have a number, and the name-brand ones, like my Cateye, are definitely more "dazzling" to the eye than the no-name cheap ones I have. I don't think it's a matter of the amount of current sent to the LED's. I just think the more expensive unit uses better quality LED's IMHO.
I think you're right that newer LED flashers, and particularly brand-name units, tend to be much brighter.
Back in the early 70 LEDs were expensive and considered pretty high-tech. The stereo system I had back then had little neon bulbs instead of LEDs.
LEDs were rare and the modern high-output LEDs were simply not available at any price. Which is why so many LED lights advertise as one and two watt. In the 80s a one watt LED was a dream. When they became commercially available in the late 90s it was a technological breakthrough and big selling point.
Of course wattage doesn't tell you much about actual light output but in the language of advertising "one watt" sounds impressive and "two watts" is, of course, better still.
As better LEDs are developed the older LED models drop in price and get incorporated into no-name devices. Brand-name producers use better LEDs. Of course I think we are coming up against other limits. How much light do you need? In urban areas with man-made light all around, and at sea where star and moonlight reflecting off waves confuses the issue, you might very well want and need a more powerful strobe. Fog and haze can also confound weaker lights.
Everything is a trade-off. Xenon strobes can be a half pound or more and they use considerable amounts of power so run times are often twenty-four hours or less.
In marine use, where weight is far less an issue, where localizing your location on vast areas of ocean is the biggest obstacle, plus the likelihood of fog and mist, I think a more powerful strobe is in order. The shorter run time may not be such a burden if you're in cold water. Even with an exposure suit if you don't get picked up in a short time you're dead.
For hiking and backpacking use, where every single gram has to be humped for miles and distances are smaller, a lighter unit or two that can ride for months unused in the bottom of a small survival kit, a unit with an extended run time seems more like the tool for the job. On land there is a good chance you can hunker down for a few days so long run time has more utility.