No it doesn't, people sticking to a class + spec + role as opposed to a class with 2 specs adds immersion. You deal with what you got and become good with that, instead of adapting to whats better. All the class homogeneity doesn't add immersion...
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If you go to a big city in the world you're facing the question what you are going to do. I'm not going to say there are 2 choices, but I will say there are a lot of options for you with 2 different extreme paths.
The first one is you taking the theme park, you do what all other have done and stick to the path as it has been drawn for you and many others. You follow the herd as sheep.
The second path is of the explorer, you explore on your own and try to visit remote locations which are not (popularly) recommended to go to.
You know, just because you visit New York, doesn't mean you gotta visit the statue of liberty.
Allowing convenience in the sense of automatic respec provides too much the theme park experience.