I guess for the same reason we didn’t upgraded to Eagle 5.
We are happy with the 4.16 version which we use and do not miss any of the new features which Eagle 5 and 6 introduce.
Each time new major version is released you have to pay new licensee fee to Cadsoft.
Eagle 4.16 installation is 5 MB and fast, Eagle 5 rise to something like 15 MB if I remember correct and we never saw something more than early bug fixes so we decided to not upgrade and pay again for something we already paid.
Now Eagle 6 is over 40 MB, let’s see what’s new:
– XML database – we never used such nor need one
– merge schematic / boards we can do it with 4.16 too with a little bit of care
– routing enhancements – we never count on autorouter
– library editor optimisations – so small that not worth mention them
– layout editor add-ons – again insignificant to adjust new payment
what I notice though is that customers who made PCB designs and submit them for production to our PCB prototype service is that Eagle 6 do not generate correct gerbers when there are polygone fills.
I attach example of PCB made with Eagle 6 which do not generate correct polygone fill which leads to shorts on copper plane.
here is example of such board
The general impression is that Eagle 6 is done in a hurry new release to shave the customers with some $$$ which the new Eagle owner obviously need after the purchase.
The bad thing is that one used to be good product before become more buggy and less useful with it’s x10 file size increase and adding useless “features” just to do new release and ask for more money.