Very good points (indeed, I totally agree on each and every of them!), but there's the risk that someone writing a software just for sake of the task will just

Very good points (indeed, I totally agree on each and every of them!), but there's the risk that someone writing a software just for sake of the task will just argue «I'm not interested in doing this, but in the task». This is exactly what happens for many users when you suggest them to install GNU/Linux and enjoy freedom. They say: «I don't want to learn another OS. I just use the computer to get things done». Then they'll keep using Excel.