Installing the avy is one of the easiest "conversions", you don't have to take apart dampers, bleed, use shock clamps, etc. You just unbolt the bottom footnut, unbolt the top cap, yank everything out, replace with avy damper. If you are sending it off to have this done, you shouldn't be adjusting any part of your bike, as it's likely far above your mechanical competency.
Actually that is not necessarily true. Some people would rather spend the money to have this done as they may not have the TIME to go through the process themselves. Yes there is downtime associated with both, but much easier for someone to send off the fork to be handled while on vacation, business trip, etc. than take the time to do it while they are home potentially eating into other precious hours. Remember, it doesn't always come down to mechanical aptitude but the other currency out there, which is TIME.
On top of that, some people just don't like to tinker, or don't have the available space to do that kind of stuff and thus, again, it is easier to send it off. I don't doubt that it is probably the EASIEST conversion but looking at it from a cost perspective for someone that may not have a lot of money to spend, the $400+ for the cartridge may or may not be worthwhile. The ability of it to be swapped to another 35mm chassis of the same dimensions IS a benefit down the road, but that is looking at it as a long term investment with the assumption that RS or FOX (whomever you buy your fork from) will keep that same chassis design in perpitude with the ever changing technology.
Careful with broad and vague assumptions, not everyone has the space, money, time, etc. to handle the same things you do. Nor do they have the same mindset as you, while the $400+ for the Avy cartridge is a justifiable expense for you, the next guy may have just spent his wad on an entire new bike (most he could afford) only to find that the fork, shock, wheels, drivetrain or whatever is not what he/she expected and needs a cheap upgrade to work as a stop gap. I know people who can throw around a grand or two to try new things out and have "extra" parts laying around, good for them and I aspire to be there one day but currently am not so I gotta deal with what I can get.
Main thing is that no one thing is right or wrong here... How does the saying going?
Opinions are like @$$holes, everyone has one. But that does not make yours any prettier (or more right) than the others.
