Flash sticks had a very finite write limitation which made them unsuitable for long term full installs. Live OSs do not write to the device.
Yes - this is the same reason why I am encountering some difficulty at present with installing to my EeePCs. Due to the background disk write activity problem with certain desktop environments, I have recently adopted the practice of installing to the SDHC card only and avoiding the onboard SSD entirely (as the card is easily replaceable, whereas the onboard SSD is not.). This method does indeed result in an install that performs more slowly; however, with all considered it seems the most prudent.
An install expects to find a specific set of hardware when it is booting, a live OS does not, which makes the live OS portable.
That is a good point JohnBoy, and one which I'd not previously considered (as my EeePCs are the only machines I have which are capable of booting from USB/SDHC.).
A flash stick can hold several live OSs and give you an option to boot into any it contains.
Again, something I'd not considered, as I'm quite happy with PCLinuxOS for nearly everything. In the instances I've encountered where PCLinuxOS is unsuitable (386-586 class machines; SCSI), such equipment usually requires booting from CD directly, anyway.
Some PCs have no optical drive ... Netbooks .... so the flash stick is the method of booting and installing.
What; no floppy? ;-)
In my situation it's usually more the case that if a particular machine has no CDROM drive, then I'll attempt to install one. With the EeePCs however, I've a bit of an unusual advantage, in that I once bought a case of twenty USB-IDE adapter cables (as they remain the only means by which to overcome the inherent 8/30/120GB BIOS disk size limitations of many of my machines), and therefore it is a simple matter for me to merely grab another CDROM drive from the pile and plug one of those adapters into it.
Booting from a USB live OS is much faster than using optical media.
It is very easy to change the OS on a flash stick.
Both quite true... in the two instances where I have performed USB installs, both did indeed boot and run more quickly. However; I had assumed that to perhaps mostly be due to my usage of proper linux filesystems in each case, as most of the 'inexpensive' sorts of USB sticks I've encountered seemed to be rather slow in data transfer rate anyway - slower, actually, than the data transfer rate I usually obtain with an external drive and adapter cable.
I suppose now that the only real advantage I could see in making use of a 'boot-stick' app would pertain entirely to your point regarding hardware specificity - is there no way, then, to perform a ('portable') 'live-CD' install to a stick by loop-mounting the .iso, copying the files contained therein to the stick, and then installing GRUB to the stick directly as well? With that method (assuming it to be possible), one then has the great advantage of installing into a proper linux filesystem.
That has always been my major point of confusion concerning the various 'boot-stick' app methods, as they all seem to require installation into a FAT-formatted device only, and I don't quite see the point to that as it is very easy to wipe such a stick with dd and then reformat it properly. A Windows-user could still boot a linux-formatted stick regardless, so why force linux into a FAT-based filesystem - especially considering the limitations of such? It just doesn't make sense to me.