Fossett hit the ground so hard that there was hardly a piece of the plane left over bigger than 1-2 feet in length. An ELT was not going to be a major issue there...
The problem with 406MHz is that it is fairly new. Very very few planes have them. I originally considered putting one in when I went N-reg and was quoted £2000 for the paperwork (well known UK shop)
The unit itself was £1500 (Artex). So I put in a cheap Artex unit which the plane was prewired for - 243+121.5MHz - for £200. It was legal....
Today you can fit a 406 for under £1k but there is another "ELT war" brewing, like the Mode S war. So most people won't have an ELT anyway.
In Europe there are very few scenarios where an ELT is going to yield statistically significant usefulness. Engine failures among the types of planes which will carry them (usually well maintained IFR tourers, basically) are very unusual.
Also, today, very few search vehicles have 406 capability. They have 121.5 but if they get a sat fix off the 406 signal but cannot find the 121.5 on their VDF, they end up wasting a lot of time. A GPS 406 unit would be better but very few fitted ones have that, due to the extra cost. A lot of handheld ones have GPS but due to the present "attitude" issues I suspect few VFR-only pilots will carry these.
I carry two 406+121.5 units, one of which has a GPS
Plus a 406+121.5 installed one (Kannad AF Compact).