Master's programs in Europe are commonly the pathway/requirement to applying for a PhD position. This supports why they might be commonplace there, but it also means the same reason would not justify the master's only programs in the US in the same way.
Yeah but as a European I think we took the wrong route. I am from Italy, and until 2001 we had 5 years undergraduate programs only. We then chose to do 3 + 2, but we should have gone with 4 + 1 years instead.
I have a BSc in Computer Engineering and I'm finishing a MSc in Computer Science. The MSc has been useless other than for being able to start doing research. I could have learned additional things in 1 more year, without repeating most of the knowledge in the other year, and then start the PhD directly. Instead I did a MSc where for 1 year I mostly repeated old topics before starting working on really new things.
I think Masters should be highly specialized for people that after a Bachelor start to work but want additional knowledge for their position.
TLDR: 4 years Bachelors -> 4 years PhD is the correct route in my opinion. We messed up in Europe
In many places, there is a distinction between "master's through research" (a gateway to PhD) and "master's through study" (more coursework, less independent research, a gateway to r-n-d-level positions in the industry).