Agreed, it is beyond me why the just can 't push out new sillicon for Maemo 5 while at the same time it is nicely maturing.

It took me till 2005 to realize that windows XP (that was also nothing more than the next iteration) ran smooth starting from 2GB RAM with my ussage behavior.
Nowadays people are still using it.

Why Maemo 5 has such a short life?

It is the software that counts in this case. I would pay for a license.
I would pay 100 euro extra to have any latest hwkb android device, plastic garbage or not, delivered with Maemo 5.

As for Nokia , a device , a software platform: The leaked 2010 jessie girl device shout have been brought to the masses to enjoy an even smoother Maemo.

that said, the screen of N900 is unbeaten. I love the capability to zoom with one hand honding the device and circular movement. An iPhone or N8 is higly frustrating in comparison and it is always a relief to return to N900.