It's natural human reactions/instinct.

Fear - Change is bad. The unknown is bad. What can't yet be seen is something to be feared.

However, humans are incredibly adaptable - if not one of the most adaptable animals on the planet. The new skills and changes and classes and what have you will be thrust upon the masses, curiousity (also a trait that humans are greatly slaves to) will test out this 'new and dangerous' thing (the changes) and then we'll adapt to use the changes in our favor.

IE - people will moan and groan at first ---> get used to the changes, and then - to a degree ---> get over it and use it to the best of their ability ---> soon, it becomes the new norm ---> but suddenly, more new things announced ---> and then rinse and repeat from step one.