The biggest benefit is that it will slow down the new generation of Bitcoin. Early adopters of the new currency will use their mining power to generate new currencies as oppose to flooding the saturated pools of bitcoin mining. This is huge because slowing down bitcoin generation gives time for the market to grow: giving time for merchants to consider accepting Bitcoins for goods and services, allowing late adopters a chance to get into the bitcoin market , and giving time for graphic card hardware manufacturers to create new more powerful/efficient gpus to support the growing difficulty of mining.
You can't slow down the bitcoin generation in the long run. If miners leave the difficulty will adjust to ensure the same number of bitcoins are being generated. This is by design.
^THIS^
How do people not get this by now???
Also.. promoting alternative chains to allow those with experience in cryptocurrencies to rip out a few dollars from some starry eyed newbies is a nasty idea which provides ammunition for bitcoin naysayers and skeptics.
Alternative currencies as experiments for particular technical and/or economic features may well be interesting.. and I've no particular concern with some people speculating/gambling on those provided they understand the risks... but to promote this sort of gambling because as you say we should not 'underestimate the stupidity of people' does not do bitcoin any good.