In precisely what way is a mainstream movie that appeals to a lot of people risky? It's the safest type of movie to produce.
I don't like movies that are watered-down in order to appeal to everybody. I know that my essentialistic crap becomes boring but I want Trek to taste like Trek. A sci-fi flick should have a distinctive sci-fi flavour and not be tailored to the taste of the average guy.
This doesn't just hold for sci-fi or Trek but all art. You don't turn down the volume of your rock band in order to attract seniors, do you?
And no, my argument has nothing to do with the popularity of Trek per se. I find it great when Trek is popular unless this very popularity is caused by watering and dumbing down.